Is your feature request related to a problem? Please describe.
Using the scrollToVerticalOffset method of the scrollview with animation enabled leaves me blind when the animation came to an end. I would need this to know if the scroll event is fired because of user interaction or by the scrollToVerticalOffset method. Overall this feature would increase control over the component.

Describe the solution you'd like
Best option in my opinion would be to return a promise when the method is called. Much like other animation functions.

Describe alternatives you've considered
Add an event when ever an animation ended. I looked into the scroll view implementation in ios and i think it would be the easiest way to just add the event in the delegate. A promise might be a little bit more elegant. Not sure about android though.

Additional context
Delegate function for ios can be found here.
If this feature is helpful for others i might do a PR, but I think i need a little hint how to make it work on android.