Do not loade web page until switching to device page (#9031)

* Do not loade web page until switching to device page

src/slic3r/GUI/PrinterWebView.hpp

@@ -43,6 +43,9 @@ public:
     void OnLoaded(wxWebViewEvent& evt);
     void reload();
     void update_mode();
+
+    bool Show(bool show = true) override;
+
 private:
     void SendAPIKey();
 
@@ -51,6 +54,8 @@ private:
     wxString m_apikey;
     bool m_apikey_sent;
 
+    wxString m_url_deferred;
+
     // DECLARE_EVENT_TABLE()
 };