qt: Replace deprecated stateChanged with checkStateChanged

Updates QCheckBox signal connections to use checkStateChanged instead of
the deprecated stateChanged signal. This change affects:

- qt_controller.cpp
- configure_filesystem.cpp
- configure_input.cpp
- configure_input_advanced.cpp
- configure_system.cpp
- configure_ui.cpp
- shared_widget.cpp

Also updates lambda signatures to use Qt::CheckState instead of int for
the state parameter where needed.

src/citron/configuration/shared_widget.cpp

@@ -699,7 +699,7 @@ void Widget::SetupComponent(const QString& label, std::function<void()>& load_fu
                 restore_func();
             }
         };
-        connect(checkbox, &QCheckBox::stateChanged, reset);
+        connect(checkbox, &QCheckBox::checkStateChanged, reset);
         reset(checkbox->checkState());
     }
 }