Convert KeyboardAvoidingView to function component

Follows the same migration as ImageBackground (#56355), RefreshControl
(#56354) and Modal (#56348).

As with ImageBackground, a ref on <KeyboardAvoidingView> now forwards to
the underlying View (exposing measure, setNativeProps, ...) instead of
the class instance, and the KeyboardAvoidingViewInstance type export is
removed.

Author: ahmdshrif