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/widgets/helper/NotebookTab.hpp

@@ -1,7 +1,6 @@
 #pragma once
 
 #include "common/Common.hpp"
-#include "widgets/BaseWidget.hpp"
 #include "widgets/helper/Button.hpp"
 #include "widgets/Notebook.hpp"
 
@@ -14,8 +13,6 @@ namespace chatterino {
 
 #define NOTEBOOK_TAB_HEIGHT 28
 
-// class Notebook;
-class Notebook;
 class SplitContainer;
 
 class NotebookTab : public Button