* Adds an option to set email through iframe API init and to stats.
* Simplifies configuring email and displayName in stats.
Removes enableStatsID as not needed as when off we are sending as callstats id xmpp resource which is unique per call and id must be something that sticks between calls (callstatsUsername).
* Adds email and displayName in stats config for mobile.
* chore(deps): Updates lib-jitsi-meet to latest dd31f0a.
* Removes enableStatsID from config and whitelist.
This refactors all handling of audio-only and last N to 2 features in preparation
for "low bandwidth mode".
The main motivation to do this is that lastN is a "global" setting so it helps
to have all processing for it in a single place.