ipc_helpers: Add PushEnum() member function to ResponseBuilder

Allows pushing strongly-typed enum members without the need to always
cast them at the call sites.

Note that we *only* allow strongly-typed enums in this case. The reason
for this is that strongly typed enums have a guaranteed defined size, so
the size of the data being pushed is always deterministic. With regular
enums this can be a little more error-prone, so we disallow them.

This function simply uses the underlying type of the enum to determine
the size of the data. For example, if an enum is defined as:

enum class SomeEnum : u16 {
  SomeEntry
};

if PushEnum(SomeEnum::SomeEntry); is called, then it will push a
u16-size amount of data.

HLE/ACC: Stub IManagerForApplication::GetAccountId to return an error.

externals: Update glad to version 0.1.25

 gl_state: Get rid of mismatched sign conversions in Apply()

filesys/loader: std::move VirtualFile instances in constructors where applicable

audout_u/audren_u: Ensure null terminators are written out in ListAudioOutsImpl(), ListAudioDeviceName(), and GetActiveAudioDeviceName()

maxwell_3d: Remove unused variable within GetStageTextures()

thread: Convert ThreadStatus into an enum class

partition_filesystem: Return pfs_dirs member variable within GetSubdirectories()

nso: Minor changes

gl_shader_decompiler: Eliminate variable and declaration shadowing

And make IManagerForApplication::CheckAvailability always return false.
Returning a bogus id from GetAccountId causes games to crash on boot.
We should investigate this with a hwtest and either stub it properly or implement it.

Keeps the OpenGL loader library up to date. Previously we were at
version 0.1.16

While we're at it, amend the loop variable type to be the same width as
that returned by the .size() call.

This avoids unnecessary atomic reference count increments and decrements

Avoids potentially unnecessary atomic reference count incrementing and
decrementing, as well as string copying.

gl_shader_decompiler: Remove unnecessary const from return values

pl_u: Simplify WriteBuffer() calls in GetSharedFontInOrderOfPriority()

std::string doesn't include the null-terminator in its data() + size()
range. This ensures that the null-terminator will also be written to the buffer

Uses a type that doesn't potentially dynamically allocate, and ensures
that the name of the interface is properly null-terminated when writing
it to the buffer.

Makes the thread status strongly typed, so implicit conversions can't
happen. It also makes it easier to catch mistakes at compile time.

This should be returned here, otherwise pfs_dirs is effectively only
ever added to, but never read.

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