[InstCombine] Fold range-with-hole test to direct inequality checks

## Description

InstCombine appears to miss:

```text
(X - C) >u N || (X - C) == K
```

when the complement is a small constant set.

Example:

```llvm
define i1 @src(i8 %x) {
%v1 = add i8 %x, -8
%v3 = icmp ugt i8 %v1, 2
%v5 = icmp eq i8 %v1, 1
%r = or i1 %v3, %v5
ret i1 %r
}

define i1 @tgt(i8 %x) {
%a = icmp ne i8 %x, 8
%b = icmp ne i8 %x, 10
%r = and i1 %a, %b
ret i1 %r
}
```

Alive2: https://alive2.llvm.org/ce/z/Da85bf

The source is false only when:

```text
x - 8 ∈ {0, 2}
```

i.e. when:

```text
x ∈ {8, 10}
```

Therefore it is equivalent to:

```c
x != 8 && x != 10
```

This removes the arithmetic and exposes a simpler constant set-membership test.

Start in InstCombine's integer comparison and arithmetic-folding handling, using the LLVM IR example in the issue as the entry point. Trace how the range-with-hole condition is represented and verify that the shown source is reduced to equivalent direct inequality checks for the stated constants.

Written by the indexing model from the issue text.