NEW:add network test entry when has network error

Change-Id: Ie315191e26148e520d3e8e3e4323fd619efb982a

src/slic3r/GUI/Jobs/NotificationProgressIndicator.hpp

@@ -15,6 +15,7 @@ public:
     explicit NotificationProgressIndicator(NotificationManager *nm);
 
     void clear_percent() override;
+    void show_networking_test() override;
     void set_range(int range) override;
     void set_cancel_callback(CancelFn = CancelFn()) override;
     void set_progress(int pr) override;