Provide a way to create outbound connections from ephemeral ports in P2P

[coot]

SPOs would like to retain the possibility of a BP node to create unidirectional connections. This allows a hot standby BP behind a firewall; once the BP needs to be activated, the firewall rules can be changed so the relays can connect to the BP and distribute its blocks:

• relays are configured to create duplex connections to the hot standup BP which are blocked by the firewall (e.g. its blocks are not reaching the relays)
• the hot standup BP is configured to create unidirectional connections to the relay (from ephemeral ports), which go through the firewall (hot standup BP needs to get blocks)

Hot standbys & the proposed solution were discussed in the recent Network Working Group meeting.

Requires:

• Modify connection manager state data type #5017