Allow component in fullscreen fade (above bottom sheet)

[aLemonFox]

It can be useful if we had an option to provide a component which is positioned above the fullscreen fade (by zIndex). I modified the code with 2 extra lines to provide this function. Is there another (better) option to do is?

E.g.:

<RBSheet
  topLayerComponent={<Text>Hello! I'm inside the fullscreen fade!</Text>}
>
  <MyNormalContent/>
</RBSheet>

This component would be placed between <KeyboardAvoidingView/> and <TouchableOpacity/> in index.js

edit: see relevant pull request: /pull/90