Support tunnels conflicting across workshops

Trying to launch a workshop that exposes a HTTP port, when another workshop already exposes it:

```
$ workshop launch
error: cannot perform the following tasks:
- Setup "system" SDK profile (The following instances failed updating (profile change still saved):
- Project: workshop.michal, Instance: dev-60bb71a8: Failed starting device "system_doc": Error occurred when starting proxy device: Error: Failed listening on 127.0.0.1:8000: listen tcp 127.0.0.1:8000: bind: address already in use
```

Workshop should deal with that since it has the context. Probably launch without auto-connecting the interface.

`workshop connect …` could then ask whether to disconnect the offending connection.

It should also be possible to redirect the tunnel to another endpoint?