Allow users to manually select webcam parameters

[DemiMarie]

For resolution and frame rate, we can make a reasonable default choice based on heuristics, such as “highest resolution, then fastest frame rate” or “fastest frame rate, then highest resolution”. However, users might very well want to override the defaults. Ideally, this could be done via a GUI, but a configuration file would be okay for now.

[DemiMarie]

From real-world experience, this is a hard requirement. My laptop’s webcam has a max resolution of 1280x720, but this causes Zoom to slow to a crawl. So it turns out that we cannot actually provide useful defaults here.

[ElliotKillick]

My computer handles 1920x1080 just fine with Zoom. Try making the video preview smaller or hiding it completely (by right-clicking). It's this playback of raw video that takes all the performance.

The only real solution for fixing the performance is switching from streaming raw video to JPEGs as we have made progress towards in #13.

Of course, this does increase attack surface but I think it's worth it. This will still be a much, much smaller attack surface than connecting the USB device from sys-usb.

[ElliotKillick]

Also, I have all 4 of my vCPUs assigned to the qube I use for Zoom.