[llvm] [AArch64] Add lowering for `@llvm.experimental.vector.compress` (PR #101015)

[David Green via llvm-commits]

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

Sorry I was not around yesterday. This LGTM from what I can tell, thanks for the updates.

https://github.com/llvm/llvm-project/pull/101015