crimson/net: fix address learning during banner exchange

crimson/net: fix address learning during banner exchange

* Don't store my_addr in `Connection`, because my_addr can be learned
  and thus changed.
* Support nonce in SocketMessenger.
* Always set nonce when set_myaddr().
* Add learned_addr() for SocketMessenger.
* Add side_t and socket_port to show the real connecting
  ports of the SocketConnection.
* Fix bannder exchange logic for addresses, including nonce, type, ip,
  port, socket_port for my_addr and peer_addr.
* Add more detailed logging prefixes for SocketConnection.

Signed-off-by: Yingxin <yingxin.cheng@intel.com>