Voice / Video channel interface options need improvment

User interface options related to voice channels and video need to be improved.

First, there should be an option to join a voice channel, while disabling the video-chat picture-in-picture window which obscures the discord interface, even when connected to the voice channel, and reading other text channels.

Second, the pop-up video chat window should be resizable to some degree.  Also, while it makes sense the popup snaps to keep it within the window frame, the forced border (area where the pop-up will slide away from the edges when attempting to move it) is grossly oversized.

Third, there should be an option to break the video chat frame out to a separate window, which would allow users to push it to a separate display screen, or implement it as part of the full-screen overlay.