feat(swarm): expose ConnectionId and add conn duration metric

- Exposes the `ConnectionId` in the various `SwarmEvent` variants.
- Tracks connection duration in `libp2p-metrics::swarm`.

Pull-Request: #3927.

protocols/perf/tests/lib.rs

@@ -53,7 +53,7 @@ async fn perf() {
         .wait(|e| match e {
             SwarmEvent::IncomingConnection { .. } => panic!(),
             SwarmEvent::ConnectionEstablished { .. } => None,
-            SwarmEvent::Dialing(_) => None,
+            SwarmEvent::Dialing { .. } => None,
             SwarmEvent::Behaviour(client::Event { result, .. }) => Some(result),
             e => panic!("{e:?}"),
         })