gl_shader_decompiler: Eliminate variable and declaration shadowing

gl_shader_decompiler: Remove unnecessary const from return values

pl_u: Simplify WriteBuffer() calls in GetSharedFontInOrderOfPriority()

Ensures that no identifiers are being hidden, which also reduces
compiler warnings.

This adds nothing from a behavioral point of view, and can inhibit the
move constructor/RVO

With the new overload, we can simply pass the container directly.

hle_ipc: Introduce generic WriteBuffer overload for multiple container types

pl_u: Specify correct size for buffers in GetSharedFontInOrderOfPriority()

HLE/ACC: Change the default user id and small improvements to the way we handle profiles

HLE/ACC: Write a single whole user id in ListAllUsers and ListOpenUsers.

pl_u: Remove printf specifier in log call in a log call in GetSharedFontInOrderOfPriority()

gdbstub: Get rid of a few signed/unsigned comparisons

hid: Resolve a signed/unsigned comparison warning

svc: Correct always true assertion case in SetThreadCoreMask

loader: Amend Doxygen comments

loader/nso: Check if read succeeded in IdentifyFile() before checking magic value

hle/service: Make constructors explicit where applicable

The default username for now is "yuzu".
We should eventually allow the creation of users in the emulator and have the ability to modify their parameters.

In IApplicationFunctions::PopLaunchParameter we tell the games that they were launched as user id 1.

We only emulate a single user id for now.

nvflinger: Emplace Display instances directly

This introduces a slightly more generic variant of WriteBuffer().
Notably, this variant doesn't constrain the arguments to only accepting
std::vector instances. It accepts whatever adheres to the
ContiguousContainer concept in the C++ standard library.

This essentially means, std::array, std::string, and std::vector can be
used directly with this interface. The interface no longer forces you to
solely use containers that dynamically allocate.

To ensure our overloads play nice with one another, we only enable the
container-based WriteBuffer if the argument is not a pointer, otherwise
we fall back to the pointer-based one.

nvdrv: Take std::string by const reference in GetDevice()

Filesystem: Return EntryType::Directory for the root directory.

This WriteBuffer overload expects its size argument to be in bytes, not
elements.

The reason this would never be true is that ideal_processor is a u8 and
THREADPROCESSORID_DEFAULT is an s32. In this case, it boils down to how
arithmetic conversions are performed before performing the comparison.

If an unsigned value has a lesser conversion rank (aka smaller size)
than the signed type being compared, then the unsigned value is promoted
to the signed value (i.e. u8 -> s32 happens before the comparison). No
sign-extension occurs here either.

An alternative phrasing:

Say we have a variable named core and it's given a value of -2.

u8 core = -2;

This becomes 254 due to the lack of sign. During integral promotion to
the signed type, this still remains as 254, and therefore the condition
will always be true, because no matter what value the u8 is given it
will never be -2 in terms of 32 bits.

Now, if one type was a s32 and one was a u32, this would be entirely
different, since they have the same bit width (and the signed type would
be converted to unsigned instead of the other way around) but would
still have its representation preserved in terms of bits, allowing the
comparison to be false in some cases, as opposed to being true all the
time.

---

We also get rid of two signed/unsigned comparison warnings while we're
at it.

This can just use the fmt specifiers and be type-agnostic.

hle_ipc: Amend usage of buffer_index within one of HLERequestContext's WriteBuffer() overloads

 fsp_srv: Misc individual changes

Ensures both operands in comparisons are the same signedness.

Modernizes the loops themselves while also getting rid of a signed/unsigned
comparison in a loop condition.

Gets rid of the use of a magic constant

filesystem: Minor changes

common/swap: Minor changes

common/common_funcs: Remove unused rotation functions

loader/{nro, nso}: Resolve compilation warnings 

It is unknown if this is correct behavior, but it makes sense and fixes a regression with Stardew Valley.

These weren't adjusted when VFS was introduced

common/misc: Deduplicate code in GetLastErrorMsg()

externals: Update Xbyak to 5.65