fix: in the swarm move Connectedness emit after releasing conns

go-libp2p-kad-dht now listen to both EvtPeerIdentificationCompleted and EvtPeerConnectednessChanged
and EvtPeerIdentificationCompleted calls .ConnsToPeer inorder to do some filtering.

However it happens that it deadlocks because if the swarm is trying to emit a EvtPeerConnectednessChanged
while the subscriber is trying to process an EvtPeerIdentificationCompleted, the subscriber is stuck on
s.conns.RLock() while the swarm wont release it before having sent EvtPeerConnectednessChanged.
Deadlock !

I havn't confirmed this fixes my bug given this takes time to reproduce, I'll startup a new experiment soon.

p2p/net/swarm/swarm.go

@@ -329,12 +329,7 @@ func (s *Swarm) addConn(tc transport.CapableConn, dir network.Direction) (*Conn,
 	}
 
 	c.streams.m = make(map[*Stream]struct{})
-	if len(s.conns.m[p]) == 0 { // first connection
-		s.emitter.Emit(event.EvtPeerConnectednessChanged{
-			Peer:          p,
-			Connectedness: network.Connected,
-		})
-	}
+	isFirstConnection := len(s.conns.m[p]) == 0
 	s.conns.m[p] = append(s.conns.m[p], c)
 
 	// Add two swarm refs:
@@ -347,6 +342,15 @@ func (s *Swarm) addConn(tc transport.CapableConn, dir network.Direction) (*Conn,
 	c.notifyLk.Lock()
 	s.conns.Unlock()
 
+	// Emit event after releasing s.conns else a subscriber that listen boths on
+	// event.EvtPeerConnectednessChanged can't call any of the swarm method that read or write.
+	if isFirstConnection {
+		s.emitter.Emit(event.EvtPeerConnectednessChanged{
+			Peer:          p,
+			Connectedness: network.Connected,
+		})
+	}
+
 	s.notifyAll(func(f network.Notifiee) {
 		f.Connected(s, c)
 	})