Auto Client/Server Mode

[achingbrain]

Go-libp2p automatically detects its public/private status. It starts in client (queries) mode and if it determines its diallable will switch to server (mounts the protocol in multistream and responds to queries).

This can also be manually set.

We can leave this as manual in JS for now. It will require some work in libp2p for address detection to get auto mode working properly.

[achingbrain]

Autonat is coming in libp2p/js-libp2p#1298

After this is merged we need to:

1. Listen for the change:addresses event emitted by the AddressManager
   a. Does the new address list contain public IPs? Are we in client mode? Enable server mode.
   b. Does the new address list not contain public IPs? Are we in server mode? Enable client mode.

[achingbrain]

This has been implemented in #473