[llvm] [DirectX][NFC] Model precise overload type specification of DXIL Ops (PR #83917)

[Justin Bogner via llvm-commits]

https://github.com/bogner approved this pull request.

LGTM with the caveat that I think we need to iterate on the design for how we handle things like `isHalfOrFloat` to be a bit more general. I'm okay with that happening in tree as you expand this to handle more operations and get a better idea of the total space.

https://github.com/llvm/llvm-project/pull/83917