[llvm] [LLVM] Add `llvm.masked.compress` intrinsic (PR #92289)

[Lawrence Benson via llvm-commits]

lawben wrote:

@arsenm @topperc @RKSimon @efriedma-quic I believe this PR is ready to go from my side, having addressed all comments so far. Is there something missing for approval?

https://github.com/llvm/llvm-project/pull/92289