[clang] [llvm] Reland "[HLSL] Implement the `reflect` HLSL function" (PR #123853)

[Farzon Lotfi via llvm-commits]

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

I'm only reviewing commit def10ad82c6e527ba5c3aa29b76041dc94acff1d
 The reasoning for the change\fix makes sense. Although I don't like the commit message.  You don't need to amend the commit, but use the github ui to fix up the commit message before merging.

https://github.com/llvm/llvm-project/pull/123853