Type improvements

[gabrielperales]

Additional Context

Hi Sergio,

I've been playing around with this library and I've been thinking about improving some types.

Right now, action types are not bound to their payload. Wouldn't be better if we can do something like?

const ACTION_NAME = duck.defineType<Payload>('ACTION_NAME')

so when I create an action I don't have to specify the payload type, but the benefit will be that in the reducer I could know the type of the action.

So for example in this code:

// ACTION CREATORS
export const completeSurvey = duck.createAction<number>(SURVEY_COMPLETED)

// REDUCER
const reducer = duck.createReducer<State>({
	[SURVEY_COMPLETED]: (state: State, action: ReturnType<typeof completeSurvey>) => {
		return {
			...state,
			[action.payload]: (new Date()).toString()
		}
	}
}, initialState)

Right now I have to specify that the action is ReturnType<typeof completeSurvey> (TypeScript can't infer the type of the action) but in the other way, TypeScript will be able to do it.