[clang] [CIR][AArch64] Add lowering for predicated SVE svdup builtins (zeroing) (PR #175976)

[Andrzej Warzyński via cfe-commits]

banach-space wrote:

Thank you for taking a look and for the suggestions, @xlauko ! Your comments should be addressed in this [commit](https://github.com/llvm/llvm-project/pull/175976/changes/8b1c6bf1a14cfe736b4461b47038570ed48dea3d).

https://github.com/llvm/llvm-project/pull/175976