Multivideo selection improvements

[bctcvai]

1.) When in a multi-video, we should be able to select a "primary" video that is used when a canvas applet is launched. 2.) We should be able to turn on/off feeds in a multi 3.) We should be able to turn on/off indicator for the name / id of a feed (e.g. identify monitors in graphics adapter settings)

It seems like these 3 issues are somewhat related and could be executed together, if a new modal is to be constructed.

A related feature is "focus", some care should be taken to make sure there is a distinction between "primary canvas" and "focused canvas" if they are not the same. It seems more logical that a focused video is made primary, than a primary video made focused.