Add a togglable "Actions" kebab menu on the right of a change, if the
currently logged in user is an admin on the tenant.
Show available actions (currently "dequeue" only) when toggled.
Clicking the "Dequeue" item opens a modal, so that the user
can confirm her decision.
Change-Id: I7c97509d62ef167ee5904a816998049d88c6b3cb
3152171aa5