Always show a menu on durable column

Summary: If you don't have any rooms, we currently show no menu and users have no logical means of closing the column. This lets "Hide Column" at least still appear. Fixes T9195

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T9195

Differential Revision: https://secure.phabricator.com/D16516