Relay migrate peers when manually disconnected

[ez1976]

Hi. i just had to upgrade the netbird version on 2 of our internal relay servers. since they serve around 17 users at the moment, the minute i wrote "netbird service stop" all the users where disconnected for about 10-15 seconds until moved to the second relay.

i think it would be a good idea for any netbird service running to check if they act as a relay, if they do and there are peers connected, to send the peers a message to reconnect to another relay and only then disconnect it from the current relay.

once all peers have been moved, only then it will take it offline. that way the users will not be disconnected and the IT wont have to wait for a time where no peers are connected