Rename CallView methods and variables to accurate reflect what they do/are
Change local-video id and class to local-media in HTML, CSS, and JS
Improve maintainability by changing CallView remote-video to remote-media
Update test description for maintainability
Rename video-area to media-display-area and fix indent for clarity
Ensure the CallView hides itself when there's no video
Remove obsolete testing/logica for hiding CallView local-video element