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

[Lawrence Benson via llvm-commits]

lawben wrote:

Adding participants from discussion: @preames @topperc @efriedma-quic @lukel97 for feedback. Please let me know if you'd be willing to review this PR. 

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