[InstCombine] Add test cases from PR62898. NFC.

This patch adds some test cases from #62898.

As nikic noted in the issue, we should start by implementing a generalization of the fold `smin(X, Y) < Z -> X < Z` when `Y > Z` is implied by constant folds/invariants/dom conditions.
```
define i1 @src(i32 %x, i32 %y, i32 %z) {
  %cmp = icmp sgt i32 %y, %z
  br i1 %cmp, label %if, label %end
if:
  %cond = call i32 @llvm.smin.i32(i32 %x, i32 %y)
  %tobool = icmp slt i32 %cond, %z
  ret i1 %tobool
end:
  ret i1 false
}

define i1 @tgt(i32 %x, i32 %y, i32 %z) {
  %cmp = icmp sgt i32 %y, %z
  br i1 %cmp, label %if, label %end
if:
  %tobool = icmp slt i32 %x, %z
  ret i1 %tobool
end:
  ret i1 false
}

declare i32 @llvm.smin.i32(i32, i32)
```
Alive2: https://alive2.llvm.org/ce/z/dK9vXz

This patch also adds some generalized test cases like the above.

Reviewed By: goldstein.w.n

Differential Revision: https://reviews.llvm.org/D156227

Author: dtcxzyw