[InstCombine] Match range check pattern with SExt (#118910)

= Background

We optimize range check patterns like the following:
```
  %n_not_negative = icmp sge i32 %n, 0
  call void @llvm.assume(i1 %n_not_negative)
  %a = icmp sge i32 %x, 0
  %b = icmp slt i32 %x, %n
  %c = and i1 %a, %b
```
to a single unsigned comparison:
```
  %n_not_negative = icmp sge i32 %n, 0
  call void @llvm.assume(i1 %n_not_negative)
  %c = icmp ult i32 %x, %n
```

= Extended Pattern

This adds support for a variant of this pattern where the upper range is
compared with a sign extended value:

```
  %n_not_negative = icmp sge i64 %n, 0
  call void @llvm.assume(i1 %n_not_negative)
  %x_sext = sext i32 %x to i64
  %a = icmp sge i32 %x, 0
  %b = icmp slt i64 %x_sext, %n
  %c = and i1 %a, %b
```
is now optimized to:
```
  %n_not_negative = icmp sge i64 %n, 0
  call void @llvm.assume(i1 %n_not_negative)
  %x_sext = sext i32 %x to i64
  %c = icmp ult i64 %x_sext, %n
```

Alive2: https://alive2.llvm.org/ce/z/XVuz9L

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