fix: white screen flickering in dark theme.

[SectionTN]

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Summary

SafeAreaProvider (and GestureHandlerRootView) backgrounds are white as default, but to remove that white flickering (or flash) when navigating you must set it color to black.

Test plan

yarn start && yarn android and test, this change is simple and it does not affect any files.

[callstack-bot]

Hey @SectionTN, thank you for your pull request 🤗. The documentation from this branch can be viewed here.

[lukewalczak]

The issue with flickering white screen was fixed in the following commit