Add numthreads to disassembly output

[bob80905]

Previously, for CS, MS, and AS shaders, the metadata at the top of the dxil disassembly would not mention anything about numthreads attributes for the respective shader, and there would be an obscure instruction in the dxil reflecting the numthreads configuration.
Now, numthreads configurations per shader (that supports it) will be seen in the disassembly spew at the top of the dxil output.

[AppVeyorBot]

✅ Build DirectXShaderCompiler 1.0.1711 completed (commit cca1cae3ca by @bob80905)

[AppVeyorBot]

✅ Build DirectXShaderCompiler 1.0.1712 completed (commit 6502f233fb by @bob80905)

[pow2clk]

Thanks for updating the description!

[AppVeyorBot]

✅ Build DirectXShaderCompiler 1.0.1721 completed (commit 27c8c6a26a by @bob80905)

[bob80905]

This PR is for #4447

[tex3d]

The first DWORD that is skipped here by offset = sizeof(unsigned) is the size of the PSVRuntimeInfo structure. Only if it is >= sizeof(PSVRuntimeInfo2) should you be casting it to that.

In fact, this should use DxilPipelineStateValidation, since it handles all this. Here's how:

DxilPipelineStateValidation PSV;
PSV.InitFromPSV0(pBuffer, uBufferSize);
const PSVRuntimeInfo0 *pInfo0 = PSV.GetPSVRuntimeInfo0();
const PSVRuntimeInfo0 *pInfo1 = PSV.GetPSVRuntimeInfo1();
const PSVRuntimeInfo2 *pInfo2 = PSV.GetPSVRuntimeInfo2();
...
if (pInfo2) {
  OS << comment << " Numthreads=(" << pInfo2->NumThreadsX << "," << pInfo2->NumThreadsY << "," << pInfo2->NumThreadsZ << ")\n";
}
...
// Example - Mesh Shader output topology:
if (pInfo1) {
  OS << comment << " MeshOutputTopology=";
  DXIL::MeshOutputTopology topology = static_cast<DXIL::MeshOutputTopology>(pInfo1->MS1.MeshOutputTopology);
  switch (topology) {
  case DXIL::MeshOutputTopology::Undefined:
    OS << "undefined\n";
    break;
  case DXIL::MeshOutputTopology::Line:
    OS << "line\n";
    break;
  case DXIL::MeshOutputTopology::Triangle:
    OS << "triangle\n";
    break;
  default:
    OS << "invalid\n";
    break;
  }
}

This requires that size be passed in here, which should be available from the part size when PSV0 part was looked up.

edited to add MeshOutputTopology example and required pInfo1.
edited to add switch for enum and change style to Name=<value> to match the rest of the disassembler here.
Note: it would be nice to create nice enum to string functions instead of switch statements inline here, but this follows the pattern of the rest of the PSV decoding in the existing code.