fix: iOS multiple windows scenario

[alexbumbu]

Using RNSFullWindowOverlay in multiple windows scenarios is causing weird presentation issues and it's causing a crash for applications which use UISceneDelegate. This is a fix I propose for these issues. For fixing this I ended up using keyWindow, even though it's deprecated starting with iOS 13. After doing some research I found that filtering for the foreground active scene, and retrieve the keyWindow this way won't cover all the cases (more details in this post: https://teng.pub/technical/2021/11/9/uiapplication-key-window-replacement).

[WoLewicki]

Seems that RN also uses this prop in their implementation: https://github.com/facebook/react-native/blob/8bd3edec88148d0ab1f225d2119435681fbbba33/React/CoreModules/RCTDevLoadingView.mm#L117 so I think it is ok to do it like that. Did you test if it does not destroy any of the current behaviors (https://github.com/software-mansion/react-native-screens/blob/cc5de7ba28e90ecce9bbb3464ef0a625eaae032f/TestsExample/src/Test1096.tsx is good for testing it)? If so, I think we can merge it.