[clang] [CIR][AArch64] Lower Vector saturating shift and narrow intrinsics (PR #209389)

[Jiahao Guo via cfe-commits]

https://github.com/E00N777 commented:

> Note, this and the following intrinsics are "rounding":
> * https://arm-software.github.io/acle/neon_intrinsics/advsimd.html#vector-saturating-rounding-shift-right-and-narrow
> 
> Would you be able to sent a separate PR for those? 

Sorry! The two tables are next to each other, and test cases look very similar, so I might mixed them. Let me fix this!



https://github.com/llvm/llvm-project/pull/209389