[InstCombine] Support minimumnum/maximumnum (#180529)
Support minimumnum/maximumnum intrinsics in various existing
minnum/maxnum/minimum/maximum folds.
The test coverage has been copied from minnum/maxnum.
Proofs: https://alive2.llvm.org/ce/z/YMlLwO
Proofs that time out: https://alive2.llvm.org/ce/z/dJN8wj
