Explain which part of the LiveKit connection failed

[robintown]

When the connection to LiveKit fails, we should try to describe exactly which part of the connection failed (the Websocket connection? A peer connection? Which peer connection?) to the best of our abilities on the error screen, under some kind of "show details" button. This will aid in debugging firewall configuration issues / lack of TURNS.

This will become more important as we try to lock down access to LiveKit more based on what homeserver users are coming from, as it may not be possible for a joining user to create the LiveKit room. (https://github.com/element-hq/voip-internal/issues/294)