yuzu qt: Save disable_web_applet setting

The web applet causes multiple issues with the rest of the application.
Disable it by default and add a debug option to re-enable it until a
proper solution can be found.

src/yuzu/uisettings.h

@@ -114,7 +114,7 @@ struct Values {
 
     bool configuration_applied;
     bool reset_to_defaults;
-    bool disable_web_applet{};
+    Settings::BasicSetting<bool> disable_web_applet{true, "disable_web_applet"};
 };
 
 extern Values values;