fix: navigation bar colors

[rnr]

This PR fixes bug with Navigation Bar background and title colors in dark mode.

By some reason calculated UIColor doesn't work for navigation bar (like Theme.Colors.textPrimary.uiColor()) and I added UIColors struct into Theme.

After fix Navigation Bar looks like this:

[saeedbashir]

@rnr I'm only able to replicate the issue when I revert the changes of CourseContainerView i.e., when I remove the background color.

Could you please check it again to see if you are able to reproduce the issue by using uiColor() in UINavigationController viewWillLayoutSubviews.

[rnr]

@rnr I'm only able to replicate the issue when I revert the changes of CourseContainerView i.e., when I remove the background color.

Could you please check it again to see if you are able to reproduce the issue by using uiColor() in UINavigationController viewWillLayoutSubviews.

@saeedbashir yes I'm able For navigationBar.titleTextAttributes = [.foregroundColor: Theme.Colors.textPrimary.uiColor()] - no title as you see:

To see problem with navigationBar.backIndicatorImage you need to change accentColor to non-blue color (because it gets default color when error):