Add accurate innerRefs to types

[martsie]

Currently when using innerRef in a Typescript project the ref provided is a generic React Element which removes the ability to do FlatList/SectionList/ScrollView methods like scrollToIndex. The PR types innerRef to the internal element that's being rendered.

[Justinohallo]

This looks good to me and would be a great addition.

[dmtuan97]

This PR will allow my project to use scrollToIndex with KeyboardAwareFlatList, I will use patch-package first. Thank @martsie