support onLayout on <View/>

[twop]

Needed for responsive layout, and VirtualList etc (also needed for layout animations in the future)

https://facebook.github.io/react-native/docs/view#onlayout

[cztomsik]

if you want to take it, it should be enough to call onLayout during Surface/TextContainer.write()

[cztomsik]

collect all the onLayout-interested views (their surface ids) and send them as part of the batch, so that all the resulting layouts can be returned and then we can invoke respective onLayout callbacks
https://facebook.github.io/react-native/docs/view#onlayout

consider adding third argument to ffi send() which would be async callback with the result

[cztomsik]

RN api was discontinued, virtual scroll will be provided by user-space libs (react-window etc.)