[Feat] useObservableState proposal

[ali-garajian]

I've found this hook to be quite useful.
The interface would be something like this

const { state, set, useValue, useOnChange } = useObservableState('initial_value');

// state.current -> current value of the state
// set -> sets the new value of the state and notifies all listeners
// useValue -> registers a listener and returns a state that causes rerender 
// useOnChange -> registers a listener and accepts a callback that gets called on updates

If you're interested I could send a PR