Naming events

[BernardoBF4]

It would be nice if we could name events to be used with the useMMKVListner, so that when we do something like this storage.set('user', JSON.stringify(user)), we could also pass a third parameter as the event name.

This is nice bacause it'd be easier to filter events on the listner hook, like a switch of ifs. In some cases, you don't want the function inside the hook to be called at every change in the storage, so you need some sort of varification for calling the function only when wanted; named events could ease that a lot.