[mlir] Fix `TileUsingForOp` attr-dict printing/parsing (#72745)

`TileUsingForOp` has an optional Attribute `interchange` which was given
in curly braces like this: `{interchange = [...]}`. The way this was
parsed meant that no normal `attr-dict` could be attached to the Op.
This patch adds printing / parsing of an `attr-dict` to the Op and treats
the `interchange` Attribute as part of that dictionary for now.