fix: make React Native work without AppDelegate window property (#49748)

Summary:
This PR makes React Native not relying on the `window` property in AppDelegate. When running in SwiftUI lifecycle mode / SceneDelegate mode there is window property on AppDelegate. This PR fixes crashes that happen because RN asserts window property is there.

## Changelog:

[IOS] [FIXED] - make React Native work without AppDelegate window property

Pull Request resolved: https://github.com/facebook/react-native/pull/49748

Test Plan: CI Green

Reviewed By: javache

Differential Revision: D70389691

Pulled By: cipolleschi

fbshipit-source-id: fe39f123b47014ba91a080239ccd298192c92a6a