Remove Unnecessary Includes in Headers (#4275)

* refactor: remove unnecessary includes in headers

* fix: formatting

* chore: changelog

* fix: scrollbar

* fix: suggestions and old appbase remains

* fix: suggestion

* fix: missing Qt forward declarations

* fix: another qt include

* fix: includes for precompiled-headers=off

* Add missing `<memory>` includes

* Add missing `#pragma once`

* Fix tests

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/BaseSettings.hpp

@@ -1,5 +1,4 @@
-#ifndef AB_SETTINGS_H
-#define AB_SETTINGS_H
+#pragma once
 
 #include "common/ChatterinoSetting.hpp"
 
@@ -46,8 +45,3 @@ Settings *getSettings();
 AB_SETTINGS_CLASS *getABSettings();
 
 }  // namespace chatterino
-
-#ifdef CHATTERINO
-#    include "singletons/Settings.hpp"
-#endif
-#endif