This saves us two x64 instructions per load/store instruction.

TODO: Clean up our memory code. We can use this optimization here as well.

The Write functions are used slightly less than the Read functions,
which make these a bit nicer to move over.

The only adjustments we really need to make here are to Dynarmic's
exclusive monitor instance. We need to keep a reference to the currently
active memory instance to perform exclusive read/write operations.

With all of the trivial parts of the memory interface moved over, we can
get right into moving over the bits that are used.

Note that this does require the use of GetInstance from the global
system instance to be used within hle_ipc.cpp and the gdbstub. This is
fine for the time being, as they both already rely on the global system
instance in other functions. These will be removed in a change directed
at both of these respectively.

For now, it's sufficient, as it still accomplishes the goal of
de-globalizing the memory code.

Amends a few interfaces to be able to handle the migration over to the
new Memory class by passing the class by reference as a function
parameter where necessary.

Notably, within the filesystem services, this eliminates two ReadBlock()
calls by using the helper functions of HLERequestContext to do that for
us.

While we're at it, this also resolves a type truncation warning as well,
given the code was truncating from a 64-bit value to a 32-bit one.

This was initially necessary when AArch64 JIT emulation was in its
infancy and all memory-related instructions weren't implemented.

Given the JIT now has all of these facilities implemented, we can remove
these functions from the CPU interface.

Prevents crash with multiprocess loading.

Our initialization process is a little wonky than one would expect when
it comes to code flow. We initialize the CPU last, as opposed to
hardware, where the CPU obviously needs to be first, otherwise nothing
else would work, and we have code that adds checks to get around this.

For example, in the page table setting code, we check to see if the
system is turned on before we even notify the CPU instances of a page
table switch. This results in dead code (at the moment), because the
only time a page table switch will occur is when the system is *not*
running, preventing the emulated CPU instances from being notified of a
page table switch in a convenient manner (technically the code path
could be taken, but we don't emulate the process creation svc handlers
yet).

This moves the threads creation into its own member function of the core
manager and restores a little order (and predictability) to our
initialization process.

Previously, in the multi-threaded cases, we'd kick off several threads
before even the main kernel process was created and ready to execute (gross!).
Now the initialization process is like so:

Initialization:
  1. Timers

  2. CPU

  3. Kernel

  4. Filesystem stuff (kind of gross, but can be amended trivially)

  5. Applet stuff (ditto in terms of being kind of gross)

  6. Main process (will be moved into the loading step in a following
                   change)

  7. Telemetry (this should be initialized last in the future).

  8. Services (4 and 5 should ideally be alongside this).

  9. GDB (gross. Uses namespace scope state. Needs to be refactored into a
          class or booted altogether).

  10. Renderer

  11. GPU (will also have its threads created in a separate step in a
           following change).

Which... isn't *ideal* per-se, however getting rid of the wonky
intertwining of CPU state initialization out of this mix gets rid of
most of the footguns when it comes to our initialization process.

Adjusts the interface of the wrappers to take a system reference, which
allows accessing a system instance without using the global accessors.

This also allows getting rid of all global accessors within the
supervisor call handling code. While this does make the wrappers
themselves slightly more noisy, this will be further cleaned up in a
follow-up. This eliminates the global system accessors in the current
code while preserving the existing interface.

Given the page table will always be guaranteed to be that of whatever
the current process is, we no longer need to keep this around.

Applies the override specifier where applicable. In the case of
destructors that are  defaulted in their definition, they can
simply be removed.

This also removes the unnecessary inclusions being done in audin_u and
audrec_u, given their close proximity.

Gets rid of the largest set of mutable global state within the core.
This also paves a way for eliminating usages of GetInstance() on the
System class as a follow-up.

Note that no behavioral changes have been made, and this simply extracts
the functionality into a class. This also has the benefit of making
dependencies on the core timing functionality explicit within the
relevant interfaces.

Places all of the timing-related functionality under the existing Core
namespace to keep things consistent, rather than having the timing
utilities sitting in its own completely separate namespace.

Added to both dynarmic and unicorn

Like the barrier, this is owned entirely by the System and will always
outlive the encompassing state, so shared ownership semantics aren't
necessary here.

There's no real need to use a shared pointer in these cases, and only
makes object management more fragile in terms of how easy it would be to
introduce cycles. Instead, just do the simple thing of using a regular
pointer. Much of this is just a hold-over from citra anyways.

It also doesn't make sense from a behavioral point of view for a
process' thread to prolong the lifetime of the process itself (the
process is supposed to own the thread, not the other way around).

Many of the member variables of the thread class aren't even used
outside of the class itself, so there's no need to make those variables
public. This change follows in the steps of the previous changes that
made other kernel types' members private.

The main motivation behind this is that the Thread class will likely
change in the future as emulation becomes more accurate, and letting
random bits of the emulator access data members of the Thread class
directly makes it a pain to shuffle around and/or modify internals.
Having all data members public like this also makes it difficult to
reason about certain bits of behavior without first verifying what parts
of the core actually use them.

Everything being public also generally follows the tendency for changes
to be introduced in completely different translation units that would
otherwise be better introduced as an addition to the Thread class'
public interface.

Makes the public interface consistent in terms of how accesses are done
on a process object. It also makes it slightly nicer to reason about the
logic of the process class, as we don't want to expose everything to
external code.

Internally within the kernel, it also includes a member variable for the
floating-point status register, and TPIDR, so we should do the same here to match
it.

While we're at it, also fix up the size of the struct and add a static
assertion to ensure it always stays the correct size.

Given games can also request a 32-bit or 39-bit address space, we
shouldn't be hardcoding the address space range as 36-bit.

Avoids an unnecessary inclusion and also uncovers three places where
indirect inclusions were relied upon, which allows us to also resolve
those.

Previously the second half of the value being written would overwrite
the first half. Thankfully this wasn't a bug that was being encountered,
as the function is currently unused.

This modifies the CPU interface to more accurately match an
AArch64-supporting CPU as opposed to an ARM11 one. Two of the methods
don't even make sense to keep around for this interface, as Adv Simd is
used, rather than the VFP in the primary execution state. This is
essentially a modernization change that should have occurred from the
get-go.

Blame the subsystems which deserve the blame :)

The updated list is not complete, just the ones I've spotted on random sampling the stack trace.

The follow-up to e2457418, which
replaces most of the includes in the core header with forward declarations.

This makes it so that if any of the headers the core header was
previously including change, then no one will need to rebuild the bulk
of the core, due to core.h being quite a prevalent inclusion.

This should make turnaround for changes much faster for developers.

Gets all of these types and interfaces out of the global namespace.

550d662 load_store_exclusive: Define s == t state to be Constraint_NONE
0b69381 A64/translate: Allow for unpredictable behaviour to be defined
6d236d4 system: Implement MRS CNTFRQ_EL0
6cbb6fb A32/testenv: Add missing headers
6729328 externals: Update xbyak to v5.67
1812bd2 Squashed 'externals/xbyak/' changes from 2794cde7..671fc805
9a95802 externals: Document subtrees
714a840 A64: Implement SQ{ADD, SUB}, and UQ{ADD, SUB}'s vector variants
8cab459 A64: Implement UQADD/UQSUB's scalar variants
18a8151 ir: Add opcodes for unsigned saturating add and subtract
a5660ee x64/reg_alloc: Use type alias for array returned by GetArgumentInfo()
29489b5 ir/value: Use type alias CoprocessorInfo for std::array<u8, 8>
e23ba26 status_register_access: Add support for bits 0 and 1 of mask to MSR
55190bd fuzz_with_unicorn: Split utility functions into fuzz_util
23b049d A32/translate/load_store: Correct detection of writeback
7ec9f15 A32/translate: Add TranslateSingleInstruction
efeecb4 A32/ir_emitter: Bug fix: IREmitter::ExceptionRaised using incorrect opcode
08d1d19 A32/decoders: Split instruction list into include file
2d929cc tests: Refactor unicorn_emu to allow for A32 unicorn
f672368 microinstruction: Improve assert messages
7ebff50 emit_x64_vector: EmitVectorNarrow16: AVX512 implementation
edce230 emit_x64_vector: EmitVectorNarrow32: prefer pblendw to loading constant

No longer required. HaltExecution is a no-op if it is not currently executing.