Please describe the feature you'd like to see added.

Split CConnman in two pieces:

• protocol agnostic low level socket and connection handler and
• bitcoin-p2p protocol specific handler.

This way the first part can be reused for Stratum V2 and for libevent-less RPC/HTTP server.

Is your feature related to a problem, if so please describe it.

Doing Stratum V2 and removing libevent from RPC requires duplicating some of the code from CConnman - binding and listening and the send/recv io loop.

Describe the solution you'd like

Split CConnman in such a way that the code can be reused.

Describe any alternatives you've considered

Duplicate code.