#90 View cleanup (Buttons, Background, ...)

Added DefaultScreenLayoutModifier (Background, AccentColor, IgnoringSafeArea)
Added View Extension defaultScreenLayout to simply add the modifier
Change Buttons in ContextMenu to Buttons/Labels in ArticleListRow
Rearrange on every View the code after mainViewComponent
- example NavigationBarTitle/Buttons/ScreenLayout/onAppear/Disapper/ listStyle/padding
Added accentColor to NavigationViewStyle
Delete much onAppears bc they are there not needed and only apply where it is needed (ContentView)
Moved Extension UINavigationController to Extensions