The way the dashboard currently does batch operations is to iterate

through the entire list of checked items and do an API call for each

one. This works OK but is quite inefficient, and our new batch view

allows doing it all in a single HTTP request.
This change moves the visibility operations (archive, mute, and

unarchive/unmute) over to that new endpoint.

Did a bunch of tests with various dashboard states and saw that

  visibility was always changed appropriately.
Ran unit tests.
Ran js-tests.