[SimplifyCFG] Emit `rotl` directly in `ReduceSwitchRange` (#77603)

This patch emits `ROTL(Cond, BitWidth - Shift)` directly in
`ReduceSwitchRange`. This should give better codegen because
`SimplifyDemandedBits` will break the rotation patterns in the original
form.

See also https://github.com/llvm/llvm-project/pull/73441 and the IR diff
https://github.com/dtcxzyw/llvm-opt-benchmark/pull/115/files.
This patch should cover most of cases handled by #73441.