Scroll to selectedOption when select is opened

## 🚀 Feature Proposal

When the last item in the list (or anyone below the cutoff) is selected and then the select list displayed again, it'd be really useful for the selected item to be scrolled into view.

## Motivation

User request https://github.com/akveo/react-native-ui-kitten/issues/794#issuecomment-570787247

## Example

https://www.loom.com/share/3a5d1df5f4b84b2297d27848aa52038b