Allows making several members of the process class private, it also
avoids going through Core::CurrentProcess() just to retrieve the owning
process.

As means to pave the way for getting rid of global state within core,
This eliminates kernel global state by removing all globals. Instead
this introduces a KernelCore class which acts as a kernel instance. This
instance lives in the System class, which keeps its lifetime contained
to the lifetime of the System class.

This also forces the kernel types to actually interact with the main
kernel instance itself instead of having transient kernel state placed
all over several translation units, keeping everything together. It also
has a nice consequence of making dependencies much more explicit.

This also makes our initialization a tad bit more correct. Previously we
were creating a kernel process before the actual kernel was initialized,
which doesn't really make much sense.

The KernelCore class itself follows the PImpl idiom, which allows
keeping all the implementation details sealed away from everything else,
which forces the use of the exposed API and allows us to avoid any
unnecessary inclusions within the main kernel header.

Using member variables for referencing the segments array increases the
size of the class in memory for little benefit. The same behavior can be
achieved through the use of accessors that just return the relevant
segment.

Removes leftover code from citra that isn't needed.

General moving to keep kernel object types separate from the direct
kernel code. Also essentially a preliminary cleanup before eliminating
global kernel state in the kernel code.

There may be many CodeSets per Process, so it's wasteful and overcomplicated to store the program id in each of them.

Threads: Added enum values for the Switch's 4 cpu cores and implemented svcGetInfo(AllowedCpuIdBitmask)

This replaces the hardcoded VRAM/DSP mappings with ones made based on
the ExHeader ARM11 Kernel caps list. While this has no visible effect
for most applications (since they use a standard set of mappings) it
does improve support for system modules and n3DS exclusives.

This makes clang-format useful on those.

Also add a bunch of forgotten transitive includes, which otherwise
prevented compilation.

We do not currently implement any cores other than the AppCore (Core 0).

Kernel/Threads: Dynamically allocate the TLS region for threads in the BASE region of the linear heap.

Each thread gets a 0x200-byte area from the 0x1000-sized page, when all 8 thread slots in a single page are used up, the kernel allocates a new page to hold another 8 entries.

This is consistent with what the real kernel does.

This also adds some basic memory usage accounting. These two types are
used by Super Smash Bros. during startup.

This adds some structures necessary to support multiple memory regions
in the future. It also adds support for different system memory types
and the new linear heap mapping at 0x30000000.

The code now properly configures the process image to match the loaded
binary segments (code, rodata, data) instead of just blindly allocating
a large chunk of dummy memory.

Implemented svcs GetResourceLimit, GetResourceLimitCurrentValues and GetResourceLimitLimitValues.

Note that the resource limits do not currently keep track of used objects, since we have no way to distinguish between an object created by the application, and an object created by some HLE module once we're inside Kernel::T::Create.