[llvm] [AMDGPU] Fold away S_AND of a lane mask with EXEC (PR #227729)

[Lukas Sommer via llvm-commits]

https://github.com/sommerlukas commented:

Implementation and new tests look good. Update to the existing tests also seems sound, some need another update to resolve merge conflicts. 

https://github.com/llvm/llvm-project/pull/227729