- users who are ejected from meeting because of permission check cannot
   rejoin meeting as we mark them as banned. Only users ejected by a
   moderator should be banned. Later on, we should make the moderator
   indicate if the ejected user should be bannd or not.

   see https://github.com/bigbluebutton/bigbluebutton/issues/9608

attack surface reduction by having akka-bbb-apps only listen on localhost

Tweaking `RegisteredUsers.remove(u.id, liveMeeting.registeredUsers)`
since we no longer have .remove on RegisteredUsers

 Do not send disconnect message when validate token fails as meteor will disconnect the client itself.

 Some users join with multiple browsers. When user is ejecting self from one browser,
 do not eject all sessions for that user and do not prevent them from rejoining.

 When a dial-in caller is ejected from the meeting, keep track of the callerid number.
 When the same callerid number rejoins the conference, eject the caller.

 - track ejected user based on external userid. If user rejoins with the same external
   userid, fail the validate token.

This reverts commit 37ed2c75, reversing
changes made to 5af41dab.

 Currently, we user DTMF to inform the client when the call session is in echo test and when entering the voice conference.
 Unfortunately, sometimes when FS sends the DTMF, FS crashes.

 Monitor the progress of the call session using ESL events and propagate to the client.

 The client would be informed of these call states: CALL_STARTED, IN_ECHO_TEST, IN_CONFERENCE, CALL_ENDED.

 - make sure listen only users are muted

 - make sure liten only user is muted when they join voice conf

Set the default recording codec to opus since we now have opus support in freeswitch.

 - set audio recording codec to ogg so file size will be smaller compared to wav