Show KeePassHTTP deprecation notice three times and use MessageWidget

src/gui/MainWindow.h

@@ -98,7 +98,6 @@ private slots:
     void hideTabMessage();
     void handleScreenLock();
     void showKeePassHTTPDeprecationNotice();
-    void openLink(const QString& link);
 
 private:
     static void setShortcut(QAction* action, QKeySequence::StandardKey standard, int fallback = 0);