Report WebRTC connection fail/timeout

Calls are unusable on the rewritten Element on a __**very high number of devices**__. Most users who use calls are **not tech-minded, so they don't even know that errors can be reported** (or even who the developers are), **they simply stop using Matrix because calls don't work.** This way, the developers can't get feedback on the ratio of success/fail from error reports. A more accurate feedback would sending events to Matomo on successful connection, and on timeout/fail. Consider that when the call is accepted, users won't wait the 20 (or 30) second network timeout, they simply end the call after 10-15 seconds of no sound. Maybe reporting the time to connect (and TURN config) would also help. (Sometimes it connects after very long amount of time, e.g. 25-30 seconds.)