[llvm] [VectorUtils] Add llvm::scaleShuffleMaskElts wrapper for narrowShuffleMaskElts/widenShuffleMaskElts (PR #96646)

[Yingwei Zheng via llvm-commits]

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

LGTM. This patch should be marked as an NFC.


https://github.com/llvm/llvm-project/pull/96646