Ensure different colored components are reflected in design system

[reillyzlab]

Historically, there has been a plan to allow nearly all of our 'components' on Drupal (and beyond) to be available in three different color options -- most easily identified as white background, dark blue background, gray background.

This work has been implemented on Drupal, but we should ensure it's in the design system.

Related: https://github.com/CityOfBoston/boston.gov-d8/issues/322