vkd3d-utils: D3DReflect() and reflection tests, part 1/2.

Unlike previous vkd3d-utils interfaces, ID3D12ShaderReflection is rather more large and complex, and will probably end up needing several new individual scan interfaces from vkd3d-shader, which are themselves not exactly trivial to design.

Therefore, instead of implementing everything in vkd3d-shader and then hooking up the vkd3d-utils interfaces on top of that, this patch series copies the existing implementation of reflection and then begins the process of moving its implementation to vkd3d-shader.

The primary motivation here is to add reflection crosstests (primarily for the benefit of the HLSL compiler) without being blocked on API design. Part 2 of this patch series does this.