[Feature request] Add support for app.8x8.vc

[supernovajm]

8x8 is the paid version of Jitsi, but the extension doesn't currently display in meetings. Meetings are run from https://app.8x8.vc/

[KopiasCsaba]

At the time of writing, I'm not even sure it is possible from an extension.

I've checked out 8x8, and it seems that it embeds into itself an iframe.

So the extension should work with data inside of that iframe, and it seems that it is a can of worms in and of itself,
not to mention to grab a MediaStream out of that up to the top level might not be possible.
(Translation: grabbing the video stream from inside a webpage that is embedding another webpage might be hard or impossible even.)

If there is enough interest in this issue, i might look deeper into that once...

Note: https://stackoverflow.com/a/13271692