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

[Nikita Popov via llvm-commits]

nikic 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.)

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