peer_connection: Fix state transition race

DTLS transport state was previously acquired and sent over to the async
context returned. This would in some rare cases obviously lead to
updating peer connection state with an old DTLS transport state.
This would in turn lead to PeerConnection not updating it's state
correctly. Sometimes we would see PeerConnection never reaching Connected.

webrtc/src/peer_connection/peer_connection_internal.rs

@@ -1168,13 +1168,13 @@ impl PeerConnectionInternal {
                 }
             };
 
+            let dtls_transport = Arc::clone(&dtls_transport);
             let ice_connection_state2 = Arc::clone(&ice_connection_state);
             let on_ice_connection_state_change_handler2 =
                 Arc::clone(&on_ice_connection_state_change_handler);
             let on_peer_connection_state_change_handler2 =
                 Arc::clone(&on_peer_connection_state_change_handler);
             let is_closed2 = Arc::clone(&is_closed);
-            let dtls_transport_state = dtls_transport.state();
             let peer_connection_state2 = Arc::clone(&peer_connection_state);
             Box::pin(async move {
                 RTCPeerConnection::do_ice_connection_state_change(
@@ -1184,6 +1184,7 @@ impl PeerConnectionInternal {
                 )
                 .await;
 
+                let dtls_transport_state = dtls_transport.state();
                 RTCPeerConnection::update_connection_state(
                     &on_peer_connection_state_change_handler2,
                     &is_closed2,