Notification Colors - dark mode validation and status colors are too subtle

[KennyAtHPE]

Related to #2425

Text color - default text Background colors - Validation Warning, Validation Critical, Background Contrast, Validation OK Status icon colors - Status Warning, Status Critical, Text Strong, Status OK

Concerns relating to the current dark mode validation and status colors:

• Default text is hard to see with the current validation colors
• Status colors blend in with validation colors
• Whether or not they do a good enough job capturing user's attention

This is affecting use cases such as global banners and form validation