Goes atop !601. The last three commits belong to this MR.
-- v2: vkd3d-shader/dxil: Implement DX intrinsic TextureStore. tests/shader-runner: Add shader model 6 texture UAV tests. tests/shader-runner: Emit descriptor ranges for consecutive resources. vkd3d-shader/spirv: Emit a vector bitcast if necessary in spirv_compiler_emit_load_ssa_reg(). vkd3d-shader/dxil: Implement DX intrinsic TextureLoad.