[DirectX] DXIL Container Support for SM 6.8 additions

[llvm-beanz]

SM 6.8 added changes to the PSV0 structures:

https://github.com/microsoft/hlsl-specs/blob/main/proposals/0012-psv0-entry-name.md

We should implement this support in the Object, ObjectYAML, and MC libraries to enable SM 6.8 code generation.

The existing tests for PSV data serialization and deserialization are here:
https://github.com/llvm/llvm-project/tree/main/llvm/test/ObjectYAML/DXContainer

[coopp]

I am currently working on this issue. The lastest PR for it is here: #84409