Light mode for individual forms

[deboer-tim]

Is your enhancement related to a problem? Please describe

Issue #6889 / PR #7149 added support to light mode for nav page and form page, but the individual form pages all have hard-coded colors (e.g. most forms have a rounded div with bg-charcoal-600).

Describe the solution you'd like

Extract any missing current colors to the registry and add light mode colors.

Priority to doing a first pass of all forms for obvious colors like the bg-charcoal-600 above, and seeing if we can now move this 'up' into FormPage. Second pass for any other obvious/common colors, then assess if there are unique forms that need more work.

Describe alternatives you've considered

No response

Additional context

No response