make operation behind gateway more user friendly

[fmoessbauer]

When operating mtda behind a ssh jumphost, multiple ports need to be forwarded. It would be good, if the number of ports could be reduced, e.g. by using a multiplexer.

Currently we have:

• www->port 9080: http / web UI
• video->port 8080: video capture (jpeg stream)
• remote->control 5556: mtda control
• remote->console 5557: mtda console
• remote->data 5558 (default: dynamic): mtda dataport (storage transfer)

The www and video port can be unified by using nginx as reverse proxy and a rewrite rule:

if ($request_uri ~ '\?action=stream') {
  set $adr http://$phost:8080;
}

[bniedermayr]

Using sshuttle on the device running the mtda cli might help here.

[chombourger]

this would get better with #569 : console and data ports were removed; we use the gRPC channel for control, console and data