feat: npt: use different session keys for each socket pair

[gkc]

- What I did

• feat: npt: use different session keys for each socket pair
• test: add end-to-end test of npt (NoPorts Tunnel)
• Resolves Different AES and IV for each socket connection via rvd in a "multi" session #866
• Resolves test: add automated end-to-end test of new "no ports tunnel" feature #890

- How I did it

• Daemon and client Currently, both sides create a control socket and authenticate
  • but there is no e2ee on the control socket
  • Change Now have e2ee on the control socket with encrypters / decrypters using the AES key and IV which were exchanged earlier via atProtocol notifications
• Client Currently, client side calls serverToSocket
  • On new local socket, sends 'connect' message on the control socket
  • Uses same encrypter & decrypter for all connections
  • Change We now generate new AES key and IV for each new connection and send it along with the 'connect' message. It's safe to do so because the control socket is now end-to-end-encrypted using session key which is exchanged via atProtocol notifications
  • Change And then, using the new 'beforeJoining' callback provided by socket_connector's serverToSocket method, we set encrypt/decrypt transformers on the new Connection's Sides before they start exchanging data
• Daemon Currently, the daemon side listens for 'connect' messages on the control socket and then creates new socket pairs all of which have the same session keys
  • Change And when we receive a connect message from the client, we use the provided AES and IV to create new encrypters / decrypters for the new socketToSocket pair

- How to verify it

• Tests pass