Handle traversal state changes and errors

Traversal connections show in the joining info UI.
Non fatal errors show the retry button.
Fatal errors end the netplay session.

Source/Android/jni/NetPlay/Netplay.cpp

@@ -8,6 +8,7 @@
 #include <jni.h>
 
 #include "Common/CommonTypes.h"
+#include "Common/TraversalClient.h"
 #include "Core/NetPlayCommon.h"
 #include "Core/Boot/Boot.h"
 #include "Core/Config/NetplaySettings.h"
@@ -194,6 +195,14 @@ Java_org_dolphinemu_dolphinemu_features_netplay_NetplaySession_nativeGetExternal
   return ToJString(env, ip);
 }
 
+JNIEXPORT void JNICALL
+Java_org_dolphinemu_dolphinemu_features_netplay_NetplaySession_nativeReconnectTraversal(JNIEnv*,
+                                                                                       jobject)
+{
+  if (Common::g_TraversalClient)
+    Common::g_TraversalClient->ReconnectToServer();
+}
+
 JNIEXPORT void JNICALL
 Java_org_dolphinemu_dolphinemu_features_netplay_NetplaySession_nativeReleaseUICallbacks(JNIEnv*,
                                                                                   jobject,