Move AS event handling from browser to view.

Having event handling in the browser made sense when the approach was to
propogate an event over to the topology, but once we switched to the
database as a single source of truth, this code became very clunky.
Moving it into the view allowed for much cleaner method and should make
debugging much easier as the code is spread across fewer files.
The function can be invoked as an event handler (i.e., by clicking on a button) or directly (i.e., toggle all other tokens to unhighlight when one is highlighted). If it's invoked directly, the action is passed in explicitly. If invoked from the DOM, it's taken off a data attribute. I'll add a comment.