onAttendeesUnmuted  
  Handles attendee(s) whose VolumeLevel has changed from muted.
Note: this callback will be called on main thread.
Parameters
attendeeInfo 
: Array<AttendeeInfo> - Attendees who are newly unmuted.
Handles attendee(s) whose VolumeLevel has changed from muted.
Note: this callback will be called on main thread.
: Array<AttendeeInfo> - Attendees who are newly unmuted.