Faulty peer disconnection notification logic

[vyzo]

If there are multiple connections to the same peer, then the disconnect notification is emitted even though the peer is still connected, breaking gossipsub's peer tracking.
See the logs in vacp2p/nim-libp2p#8

[vyzo]

Also of note that the peer connection event is emitted twice as well.

[vyzo]

related: #117

[vyzo]

Upon reflection, the issue here is that our peer management is completely incapable of handling multiple connections to the same peer.
The connection notification is emitted twice, which results in two sets of readers and writers, each of which can emit a peerDead event on failure.
So once the host closes one of the two connections, we are guaranteed to declare the peer dead even if the peer is still connected with the other connection.

We will need to completely rework on peer management logic it seems.

[vyzo]

cc @cheatfate

[vyzo]

Source issue confirmed as fixed by @cheatfate; closing.