Allow Creation of new CTA Reporting Category without creation of new CTA Type

In the old interface, admins could create a new reporting category from Administration → Calls to Action (CTAs) → “Reporting Categories” button.

Since the move to and revamp of Administration → Cockpit, we can only create a new reporting category when create a new CTA type. This limits admins from being able to properly retroactively categorize CTAs for reporting should something business critical change. 

This idea is a request to reinstate previously existing functionality. It is raised as a follow-up to this question where ​@nuts asked how to add a new category.