[llvm] [InstCombine] Fold `switch(rol(x, C1)) case C2:` to `switch(x) case rol(C2, -C1):` (PR #86307)

[via llvm-commits]

goldsteinn wrote:

> This change looks fine, although it would be nice if we had some helper generically detecting if an op is reversable so we could generalize all these cases.

Would also be useful for things like `icmp eq/ne X, C`

https://github.com/llvm/llvm-project/pull/86307