[Feature Request] Add async support for RebindingOperation in InputSystem

[dvsilch]

Currently, the RebindingOperation in the InputSystem does not natively support asynchronous operations. This feature would allow the use of UniTask when performing interactive rebinding, making it easier to integrate into async/await workflows.

For example, the proposed usage would look like:

int bindingIndex = 0;
InputAction inputAction = something;
var rebindingOperation = await inputAction.PerformInteractiveRebinding(bindingIndex).Start().ToUniTask(cancellationToken)

This would enable cleaner and more efficient async rebinding flows, especially in environments where UniTask is heavily used.

I have already implemented this feature locally. If this is something you'd like to see in the project, I would be happy to submit a pr.