[clang] [clang][clangir] add vpaddl and vpaddlq support (PR #191845)

[via cfe-commits]

xiongzile wrote:

> I've left some minor comments inline. Some variants from https://arm-software.github.io/acle/neon_intrinsics/advsimd.html#pairwise-addition-and-widen are still missing - are you planning to add them in a separate PR?

Got it. I'll extend this PR to include the remaining variants.


https://github.com/llvm/llvm-project/pull/191845