Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/36215
When we introduced the RCTAppDelegate library, we prepared some template methods for the user to customise their views.
However, after they customized their view, we were chaing the background color to match the system background. This would actually override the background color they set in their own customisation step.
This change make sure that we set the background color before they apply their customisations. In this way, we set the background color and, if they want, they can change it and that changw would be honoured.
This change also fixes [this issue](https://github.com/facebook/react-native/issues/35937)
## Changelog
[iOS][Fixed] - Honour background color customisation in RCTAppDelegate
Reviewed By: cortinico
Differential Revision: D43435946
fbshipit-source-id: cdbdbd5b07082ae7843a4dab352dd1195c69e036
Riccardo Cipolleschi
5d6f21d744