[llvm] [IR][NFC] Add LoadStoreInstAttributes to copy load/store attrs (PR #206470)

[Harrison Hao via llvm-commits]

harrisonGPU wrote:

> Would it make sense to also cover AtomicRMW, or would be rather keep that separate? (CmpXChg is a bit different because it has success and failure orderings.)

Okay, I will try to do it. :-)

https://github.com/llvm/llvm-project/pull/206470