support onAnimationEnd

[EyMaddis]

This PR allows to correctly track if the toggle animation has ended.
It is relevant when trying to apply heavy layouts after the animation is done, avoiding stutter since the height animation is not possible through useNativeDriver.

The start of an animation is easily trackable, because the parent component triggers the collapse, so there is no need for onAnimationStart.

The same was implemented for the Accordion, but since it can trigger multiple collapses, it will trigger the callback for each one. In order to keep track of this, the callback receives the current section and index as parameters.

[iRoachie]

Seems like a good use case. My only change is that I’d like for you to add defaultProps for both of them, since this will error if they don’t pass in this prop.

[EyMaddis]

@iRoachie done