qt: Persist Mask Values option

The mask values option is memory only. If a user has enabled this
option, it's reasonable to expect that they would want to have it
enabled on the next start.

src/qt/bitcoingui.cpp

@@ -647,6 +647,8 @@ void BitcoinGUI::setClientModel(ClientModel *_clientModel, interfaces::BlockAndH
             // initialize the disable state of the tray icon with the current value in the model.
             trayIcon->setVisible(optionsModel->getShowTrayIcon());
         }
+
+        m_mask_values_action->setChecked(_clientModel->getOptionsModel()->getOption(OptionsModel::OptionID::MaskValues).toBool());
     } else {
         if(trayIconMenu)
         {