vkd3d-shader/dxil: Emit the shader instructions.
Sufficient for compiling a no-op pixel shader.
This should probably be rebased on top of !263 (closed) because it introduces vkd3d_spirv_get_type_id_for_data_type(), which 263 renders unnecessary.
!263 (closed) is not essential, but I think using two different type systems in the backend is not ideal.