feat: improve p2p application handshake #1783

Background

In #1764 we added a mechanism to not accept new incoming requests from peers we are already connected to.
While this is expected so solve the network connection issues we observed in the past, it is not ideal from a performance perspective, as it's possible the sender closed the previous connection and wants to establish a new one, without the receiver knowing.

A more intelligent approach is to send the version number with the connection request, as proposed in #1759. This allows the receiver to make an educated decision as to which connection to keep.
We couldn't implement that solution at the time, because it was blocked by #1778, which needed to be included in a release first.

User Story

As a dev and node operator, I like backwards-compatible network protocols

Acceptance Criteria

Improve the handshake:

• if the application level p2p handshake passes, it should mean that either:
  • the peer is running an old protocol version, which is supported
  • the peer is running the current protocol version an this connection is good to keep (i.e. replace the incoming / outgoing connection pointer with this one).

Resources & Additional Notes

No response