[X86] canonicalizeShuffleWithBinOps - generalize to handle some unary ops

Rename to canonicalizeShuffleWithOp and begin adding SHUFFLE(UNARYOP(X),UNARYOP(Y)) -> UNARYOP(SHUFFLE(X,Y)) fold support.

This is only kicking in after legalization, so targets that expand bit counts are still duplicating but it helps with a few initial cases.

I'm investigating adding support for extensions/conversions as well, but this is a first step.