Coupled (training / E-P) mode

[maxlk96]

Probably very far in the future, but:
A coupled mode, either for training (mentor-student) or planner-executive operations.

Is your feature request related to a problem? Please describe.
When mentoring, you won't hear calls done in VACS by your student. When coordinating via TeamSpeak/Discord this is not an issue.

Describe the solution you'd like
Suggested behaviour:

1. Student controller connects as normal
2. Mentor bridges to the students connection - Maybe:
   • having a panel in the settings view where the mentor inputs the students CID
   • this prompts the student to accept/deny the connection request
   • the connection is now bridged, indicated by something special in the user box (top left, where your own freq and position is shown).
3. When mentor is connected, he'll automatically join the calls being made by the student (and optionally can talk), but should probably not be allowed to make calls for the student?
4. When student terminates his main connection, the bridging is also terminated.

Additional context
This would probably be a feature following group call functionality, when/if that happens!

[MorpheusXAUT]

See comment in #301 (comment): would definitely be great to have, but is not easily supported with our current peer-to-peer call implementation, so we'll keep it in the pipeline for potential support later.
It would be awesome to have though, but we'll have to see if it's technically feasible.

Would definitely require group calls functionality (even if normal group calls are not added).