Support native events

## Describe the Feature

**Native Events** instead of ~js events~:
`onValueChange`
`onSlidingStart`
`onSlidingComplete`

## Possible Implementations

Supporting **native events** will unlock the abilities of `Animated.event` enabling tracking the Slider's value and animating stuff accordingly.
This will enable customizing this view to a large extent easily and with high performance.

Avoiding breaking changes can be achieved with a flag from props or by checking `typeof props.onValueChange === 'object'`

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### Android JS Impl
Uses `Slider` for `value` and renders the rest on top.
Native events will enhance this extremely and make *dev experience* easier (less code needed for customization)


## Related Issues

Start by tracing the Android JS implementation described in the issue, especially how Slider value changes and the listed events are wired. Compare the current JavaScript events with React Native native-event handling and determine how Animated.event should receive the slider updates. Done means the three native events work without breaking existing JavaScript event users.

Written by the indexing model from the issue text.