Log ICE candidates when closing the peer connection. (#2105)

There are cases that experience the signalling channel timeout
and disconnect and there are no logs of what the state of ICE at all.
Log ICE candidates when closing transport so that there is some
visibility in those cases.
n

pkg/rtc/transport.go

@@ -1443,6 +1443,7 @@ func (t *PCTransport) processEvents() {
 
 	t.clearSignalStateCheckTimer()
 	t.params.Logger.Debugw("leaving events processor")
+	t.handleLogICECandidates(nil)
 }
 
 func (t *PCTransport) handleEvent(e *event) error {