Minor fixes when reporting T141

* user authenticated must be enabled/valid
* Read only: BlackMisc::CDataReadOnly<BlackCore::Data::TAuthenticatedDbUser>
* clear user fields when not authenticated

src/blackgui/components/dblogincomponent.cpp

@@ -155,6 +155,8 @@ namespace BlackGui
             }
             else
             {
+                ui->le_Name->clear();
+                ui->te_Roles->clear();
                 this->setModeLogin(true);
             }
         }