Rewriter generate consistent bindings

[Nielsbishere]

This adds functionality to dxr.exe to use -consistent-bindings, which will generate bindings for registers and constant buffers without registers assigned. This is step 1/2 to fix #5105.

The problem is if for example you have 10 textures in an include without a binding but with a space (this is how I implement bindless); it won't actually work, because all shaders respond to it differently because register bindings are generated when the optimized IR is generated (from what I understand). This is solved with the consistent bindings, because this space will have those bindings generated before going through to DXIL.

Example: dxr -consistent-bindings myFile.hlsl:

Texture2D a;
Texture2D b;
RWTexture2D<float4> c;

[numthreads(1,1,1)]
void main() {
   c[0.xx] = b[0.xx];
}

[numthreads(1,1,1)]
void main2() {
   c[0.xx] = a[0.xx];
}

Would generate:

Texture2D a : register(t0);
Texture2D b : register(t1);
RWTexture2D<float4> c : register(u0);

[numthreads(1,1,1)]
void main() {
   c[0.xx] = b[0.xx];
}

[numthreads(1,1,1)]
void main2() {
   c[0.xx] = a[0.xx];
}

So if it's compiled as lib (with [shader] annotations) or if main2 and main are compiled as compute, they'll all provide identical bindings.

Currently this is done by our own preprocessor, but I want to move that behavior into the rewriter to generate more consistent results (and to avoid having to parse HLSL manually).