[LegalizeDAG] Implement promotion rules for SELECT_CC

Implement the promotion rule for SELECT_CC nodes by upcasting all the parameters and downcasting the result.
The AArch64 target makes use of this rule and, since it was not implemented, in some cases the instruction selector would hit an assertion upon encountering the illegal node.

This patch requires D97840, the included test cases hit both problems.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D97859