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. Testing Done: - Did a bunch of tests with various dashboard states and saw that visibility was always changed appropriately. - Ran unit tests. - Ran js-tests.