Summary:
In the current implementation of the `VirtualizedList` the `onViewableItemsChanged` callback wouldn't trigger if the underlying list data changes. (see example snack https://snack.expo.io/Hk5703eBb)
I added a method in the `ViewabilityHelper` to invalidate the cached viewableIndices, which gets triggered when the list-data changes.
Closes https://github.com/facebook/react-native/pull/14922
Differential Revision: D5864537
Pulled By: sahrens
fbshipit-source-id: 37f617763596244208548817d5b138dadc12c75d
Summary: FlatList only supports one viewability configuration and callback. This change extends FlatList and VirtualizedList to support multiple viewability configurations and corresponding callbacks.
Reviewed By: sahrens
Differential Revision: D5720860
fbshipit-source-id: 9d24946362fa9001d44d4980c85f7d2627e45a33