This makes the actions more consistent, and also allows for separating
the two behaviors: The one where we need a link to a destination
(User page, diff, etc) and one where we have an action the code needs
to take care of ("Mark as read" or, in the future, volume control, etc)
Also, this allows for adding descriptions to the secondary links in
the dotdotdot menu.
It also fixes the bug where the links did not work.
Bug: T125160
Change-Id: I0ebf3fc62425f86e2e7f1e96b67f8dc34db83efb