Re-add destructuring of dispatch.

[quisido]

React's native useReducer returns [ state, dispatch ].

When using a property reducer, we can return a destructurable dispatch function, such that both of the following are valid:

const dispatch = useDispatch(propertyReducer, 'propertyName');

and

const [ propertyValue, dispatch ] = useDispatch(propertyReducer, 'propertyName');

We want to be sure the Component does not subscribe to state changes in the first case, but does in the second case.