Consider changing table header row to an active/accent color

A request from SSB to change the table header row to a more active color, so that it looks less like a disabled element.

We should consider adding this change to the standard table component in Altinn (in figma) as I think it would help refresh the design of the tables and keep it in line with other components.


Start by reviewing the linked image and the standard table component in Altinn Figma, then locate the corresponding table implementation in app-frontend-react. Done means the table header uses an agreed active/accent color instead of appearing disabled, with the standard component and frontend kept in line.

Written by the indexing model from the issue text.