vkd3d-shader/tpf: Compile HLSL to tpf through vsir, part 3.
This MR just translates swizzles to the vsir_program, allows inlining constants as instruction srcs, and begins setting up some of the functions required to translate other expressions, using ABS as the first of the flock.
Patches for further expressions are in my hlsl2vsir2tpf_2 branch.