[DAG] MatchRotate - support rotate-by-constant of illegal types

Patch to fix some of the regressions in D77804.

By folding to rotate/funnel-shift by constant amounts for illegal types, we prevent SimplifyDemandedBits from destroying the patterns prematurely, allowing us to use the rotate/funnel-shift legalization that was added in D112443.

Differential Revision: https://reviews.llvm.org/D113192