[llvm] [VectorCombine] Support pattern `bitop(cast(x), C) -> cast(bitop(x, InvC))` (PR #155216)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon commented:

Still would prefer that this PR just handles bitcasts and use followup PRs to add trunc/ext handling

https://github.com/llvm/llvm-project/pull/155216