Add code required to use OpenGL assembly programs based on
NV_gpu_program5. Decompilation for ARB programs is intended to be added
in a follow up commit. This does **not** include ARB decompilation and
it's not in an usable state.

The intention behind assembly programs is to reduce shader stutter
significantly on drivers supporting NV_gpu_program5 (and other required
extensions). Currently only Nvidia's proprietary driver supports these
extensions.

Add a UI option hidden for now to avoid people enabling this option
accidentally.

This code path has some limitations that OpenGL compatibility doesn't
have:
- NV_shader_storage_buffer_object is limited to 16 entries for a single
OpenGL context state (I don't know if this is an intended limitation, an
specification issue or I am missing something). Currently causes issues
on The Legend of Zelda: Link's Awakening.
- NV_parameter_buffer_object can't bind buffers using an offset
different to zero. The used workaround is to copy to a temporary buffer
(this doesn't happen often so it's not an issue).

On the other hand, it has the following advantages:
- Shaders build a lot faster.
- We have control over how floating point rounding is done over
individual instructions (SPIR-V on Vulkan can't do this).
- Operations on shared memory can be unsigned and signed.
- Transform feedbacks are dynamic state (not yet implemented).
- Parameter buffers (uniform buffers) are per stage, matching NVN and
hardware's behavior.
- The API to bind and create assembly programs makes sense, unlike
ARB_separate_shader_objects.

Add settings for assembly shaders. Currently hidden to avoid users from
accidentally enabled them.

FS: Improve emulation of device saves

nv_flinger: Use enum for pixel format instead of u32

DmaPusher: Remove dead code in step

vk_rasterizer: Match OpenGL's FlushAndInvalidate behavior

Match OpenGL's behavior. This can fix or simplify bisecting issues on
Vulkan.

Frontend: Remove tracking for context wrapper

audio_renderer: Better voice mixing and 6 channel downmixing

Improve time zone support

shader_ir: Add separate instructions for ordered and unordered comparisons and fix NE on GLSL

vk_graphics_pipeline: Implement rasterizer_enable on Vulkan

Stub hid:SendKeyboardLockKeyEvent

Supersedes #3738 and #3321

Needed for Puchikon 4 SmileBASIC 1.0.0

CI: Don't check clang format on early access builds

"Not equal" operators on GLSL seem to behave as unordered when we expect
an ordered comparison.

Manually emulate this checking for LGE values (numbers, not-NaNs).

externals: Cmake version checks

texture: Implement R8G8UI

This allows us to use native SPIR-V instructions without having to
manually check for NAN.