[llvm] [AArch64][SVE] Add codegen support for partial reduction lowering to wide add instructions (PR #114406)

[Benjamin Maxwell via llvm-commits]

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

LGTM (just one nit). I'd wait for @huntergr-arm to approve before landing though :slightly_smiling_face: 

https://github.com/llvm/llvm-project/pull/114406