[llvm] [Intrinsics][AArch64] Add intrinsic to mask off aliasing vector lanes (PR #117007)

[Sander de Smalen via llvm-commits]

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+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
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sdesmalen-arm wrote:

nit: maybe merge this file with alias_mask_nosve2.ll and have two RUN lines?
(in that case, would expand_alias_mask.ll` be a better name?)

https://github.com/llvm/llvm-project/pull/117007