Reapply [RISCV] Fold binary op into select if profitable.

This fixes some bugs in the original commit:
  (1) Operands are passed in correct order when creating new constant
  and the binary operator. New tests were added to cover these cases.
  (2) Check was added to see if it is safe to commute the select and the binary operator.

Reviewed By: Craig Topper

Differential Revision: https://reviews.llvm.org/D152147