Goes atop !681. The last 7 commits belong here.
-- v2: vkd3d-shader/spirv: Emit a warning if atomic RMW flags are unhandled. vkd3d-shader/dxil: Implement the DXIL ATOMICRMW instruction. vkd3d-shader/dxil: Implement DX instructions ThreadId, GroupId, ThreadIdInGroup and FlattenedThreadIdInGroup. tests/shader-runner: Add TGSM tests. vkd3d-shader/dxil: Emit an error if a constant code is unhandled. vkd3d-shader/spirv: Do not assert if a TGSM store data register is not UINT. vkd3d-shader/spirv: Do not assert if a TGSM load dst register is not UINT.