Goes atop !681. The last 8 commits belong here.
-- v4: 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.