[Do not merge, unstable code] Linux direct mode driver

[Meister1593]

I tried to upstream old linux-direct-mode branch to latest (manually, by moving separate changes, one by one), along with openvr sdk update.

Had to get around of the fact that clangd doesn't really work in ALVR codebase properly (due to missing bindings at runtime, some other stuff), but going through compile errors resulted in this PR state right now.

Most likely missed few things here and there, but at least it compiles now, should be a starting point to finish implementation.

Steamvr 307 error with this in vrcompositor.txt

Fri Aug 01 2025 16:58:03.337349 [Error] - AllocateMemory: Failed to determine a compatible memory type
Fri Aug 01 2025 16:58:03.337370 [Error] - CreateBuffer: failed to allocate buffer memory
Fri Aug 01 2025 16:58:03.337382 [Error] - Failed to init graphics device
Fri Aug 01 2025 16:58:03.356138 [Info] - Failed to kill gpu-trace

@The-personified-devil help would be greatly appreciated

[Meister1593]

For some reason this needs to be vk::detail:: instead of vk:: on my arch machine...

[Meister1593]

Most likely vulkan sdk update?