Fix some iOS 15 scrollEdgeAppearance related problems with the app's nav and tab bars. They turned black when at the top or bottom edges of scrolling content.
Add an override of UINavigationController.preferredStatusBarStyle that defaults to .lightContent
Add a nav bar appearance incantation to didFinishLaunching
Define standard and scroll edge appearance for the app's main tab bar
Fix some iOS 15 scrollEdgeAppearance related problems with the app's nav and tab bars. They turned black when at the top or bottom edges of scrolling content.