Build a new workflow that adds a dropdown in place of the old assign button with the ability to
Re-assign a new user / group to an assigned topic
Re-assign yourself to an assigned topic
Unassign a user / group from an assigned topic
Change `topic_id` to polymorphic approach (In the next step we will allow assigning to individual post)
`topic_id` column is still used for efficient display of assigned users on topic list (to avoid scanning posts)
janzenisaac
Krzysztof Kotlarek