The swap should not be concerned with connection handling. This is
the responsibility of the overall application.
All but the execution-setup NetworkBehaviour are `request-response`
behaviours. These have built-in functionality to automatically emit
a dial attempt in case we are not connected at the time we want to
send a message. We remove all of the manual dialling code from the
swap in favor of this behaviour.
Additionally, we make sure to establish a connection as soon as the
EventLoop gets started. In case we ever loose the connection to Alice,
we try to re-establish it.
As Bob is dialing Alice, we now ensure that we are connected to Alice
at each step that needs communication.
If we are not connected, we proceed with dialing.
In an attempt to improve libp2p usage, we also add known address of
Alice first and only use peer_id to dial.
This ensures that we use the expected peer id.
