maxwell_3d: Allow texture handles with TIC id zero

gl_rasterizer: Use DSA for textures and move swizzling to texture state

Port citra-emu/citra#4586: "Use QPixmap/QIcon for background color selection button"

Port citra-emu/citra#4583: "citra_qt: Fix saving screenshot when no file extension is provided"

service/nvflinger, service/vi: Improve error case handling

QT: Fix the loading screen 'H' switch logo to not glitch out

Converts many of the Find* functions to return a std::optional<T> as
opposed to returning the raw return values directly. This allows
removing a few assertions and handles error cases like the service
itself does.

video_core/texture: Fix BitField size for depth_minus_one

This member function doesn't actually modify instance state, so it can
be marked as a const member function.

This was missed within #2075. Renames the member function to make it
consistent with the rest of the Find* functions.

 shader_ir/memory: Add LD_L 64 bits loads 

Fix TXQ not using the component mask.

Co-Authored-By: FernandoS27 <fsahmkow27@gmail.com>

Also remove "enabled" field from Tegra::Texture::FullTextureInfo because
it would become unused.

shader_ir: Unify constant buffer offset values

hwopus: Implement DecodeInterleaved (the newest variant)

gl_rasterizer: Workaround invalid zeta clears

kernel: Remove the Timer class

video_core: Remove unused Fill related code

A holdover from citra, the Horizon kernel on the switch has no
prominent kernel object that functions as a timer. At least not
to the degree of sophistication that this class provided.

As such, this can be removed entirely. This class also wasn't used at
all in any meaningful way within the core, so this was just code sitting
around doing nothing. This also allows removing a few things from the
main KernelCore class that allows it to use slightly less resources
overall (though very minor and not anything really noticeable).

service: Update function tables

kernel/wait_object: Devirtualize functions related to manipulating the thread list directly

service/nvflinger: Minor renaming changes