[MLIR][Python] Add bindings for PDL native rewrite function registering (#159926)

In the MLIR Python bindings, we can currently use PDL to define simple
patterns and then execute them with the greedy rewrite driver. However,
when dealing with more complex patterns—such as constant folding for
integer addition—we find that we need `apply_native_rewrite` to actually
perform arithmetic (i.e., compute the sum of two constants). For
example, consider the following PDL pseudocode:

```mlir
pdl.pattern : benefit(1) {
  %a0 = pdl.attribute
  %a1 = pdl.attribute
  %c0 = pdl.operation "arith.constant" {value = %a0}
  %c1 = pdl.operation "arith.constant" {value = %a1}

  %op = pdl.operation "arith.addi"(%c0, %c1)

  %sum = pdl.apply_native_rewrite "addIntegers"(%a0, %a1)
  %new_cst = pdl.operation "arith.constant" {value = %sum}

  pdl.replace %op with %new_cst
}
```

Here, `addIntegers` cannot be expressed in PDL alone—it requires a
*native rewrite function*. This PR introduces a mechanism to support
exactly that, allowing complex rewrite patterns to be expressed in
Python and enabling many passes to be implemented directly in Python as
well.

As a test case, we defined two new operations (`myint.constant` and
`myint.add`) in Python and implemented a constant-folding rewrite
pattern for them. The core code looks like this:

```python
m = Module.create()
with InsertionPoint(m.body):

    @pdl.pattern(benefit=1, sym_name="myint_add_fold")
    def pat():
        ...
        op0 = pdl.OperationOp(name="myint.add", args=[v0, v1], types=[t])

        @pdl.rewrite()
        def rew():
            sum = pdl.apply_native_rewrite(
                [pdl.AttributeType.get()], "add_fold", [a0, a1]
            )
            newOp = pdl.OperationOp(
                name="myint.constant", attributes={"value": sum}, types=[t]
            )
            pdl.ReplaceOp(op0, with_op=newOp)

def add_fold(rewriter, results, values):
    a0, a1 = values
    results.push_back(IntegerAttr.get(i32, a0.value + a1.value))

pdl_module = PDLModule(m)
pdl_module.register_rewrite_function("add_fold", add_fold)
```

The idea is previously discussed in Discord #mlir-python channel with
@makslevental.

---------

Co-authored-by: Maksim Levental <maksim.levental@gmail.com>