[iOS] Handle FullWindowOverlay as the native root (#4039)

Current logic dedicated to handling `RNRootViewGestureRecognizer` on iOS
looks only for RN's native roots. When gestures are used inside Screens'
`FullWindowOverlay`, the logic doesn't do anything, but the overlay has
its own
[`RCTSurfaceTouchHandler`](https://github.com/software-mansion/react-native-screens/blob/be64b6d9a17c3a4647806f252e075b96b9f690cc/ios/RNSFullWindowOverlay.mm#L158).

This PR updates the traversal logic so it handles
`RNSFullWindowOverlayContainer` the same way as `RCTSurfaceView`.

I wasn't able to reproduce the problem, but in theory, it's possible
that without this change, recognizers from RNGH and
RCTSurfaceTouchHandler could run simultaneously, since this path never
ran:
https://github.com/software-mansion/react-native-gesture-handler/blob/5587435679eabe3f8690f077ba7c2ecc3e354a14/packages/react-native-gesture-handler/apple/RNRootViewGestureRecognizer.m#L55-L63

Author: j-piasecki