vkd3d-shader/tpf: Support non-constant offset dereferences, v2, part 2.
This is the last thing needed to support non-constant offset dereferences in SM4. It allows to perform relative addressing on temps.
Besides this, I have additional patches for relative addressing on uniforms, and input and output semantics, but these may not be useful for now, since we copy all these variables into temps instead of using them directly.