refactor: some more Application refactors (#5551)

src/common/ChatterinoSetting.hpp

@@ -141,4 +141,14 @@ public:
     using pajlada::Settings::Setting<QString>::operator QString;
 };
 
+template <typename T>
+struct IsChatterinoSettingT : std::false_type {
+};
+template <typename T>
+struct IsChatterinoSettingT<ChatterinoSetting<T>> : std::true_type {
+};
+
+template <typename T>
+concept IsChatterinoSetting = IsChatterinoSettingT<T>::value;
+
 }  // namespace chatterino