[clang] [clang][HLSL] Add sign intrinsic part 3 (PR #101989)

[Farzon Lotfi via cfe-commits]

farzonl wrote:

@tgymnich with part 1 and 2 merged I think we are ready for this. If you fix the conflicts in the PR i'll merge it for you.

https://github.com/llvm/llvm-project/pull/101989