[mlir][ptr] Add `ptr.ptr_diff` operation (#157354)

Thi patch introduces the `ptr.ptr_diff` operation for computing pointer
differences. The semantics of the operation are given by:
```
The `ptr_diff` operation computes the difference between two pointers,
returning an integer or index value representing the number of bytes
between them.

The operation supports both scalar and shaped types with value semantics:
- When both operands are scalar: produces a single difference value
- When both are shaped: performs element-wise subtraction,
  shapes must be the same

The operation also supports the following flags:
- `none`: No flags are set.
- `nuw`: No Unsigned Wrap, if the subtraction causes an unsigned overflow,
  the result is a poison value.
- `nsw`: No Signed Wrap, if the subtraction causes a signed overflow, the
  result is a poison value.

NOTE: The pointer difference is calculated using an integer type specified
by the data layout. The final result will be sign-extended or truncated to
fit the result type as necessary.
```

This patch also adds translation to LLVM IR hooks for the `ptr_diff` op.
This translation uses the `ptrtoaddr` builder to compute only index bits
difference.

Example:
```mlir
llvm.func @ptr_diff_vector_i32(%ptrs1: vector<8x!ptr.ptr<#llvm.address_space<0>>>, %ptrs2: vector<8x!ptr.ptr<#llvm.address_space<0>>>) -> vector<8xi32> {
  %diffs = ptr.ptr_diff %ptrs1, %ptrs2 : vector<8x!ptr.ptr<#llvm.address_space<0>>> -> vector<8xi32>
  llvm.return %diffs : vector<8xi32>
}
```
Translation to LLVM IR:
```llvm
define <8 x i32> @ptr_diff_vector_i32(<8 x ptr> %0, <8 x ptr> %1) {
  %3 = ptrtoint <8 x ptr> %0 to <8 x i64>
  %4 = ptrtoint <8 x ptr> %1 to <8 x i64>
  %5 = sub <8 x i64> %3, %4
  %6 = trunc <8 x i64> %5 to <8 x i32>
  ret <8 x i32> %6
}
```

---------

Co-authored-by: Mehdi Amini <joker.eph@gmail.com>

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