refactor: move Notebook enums to their own file (#6220)

Co-authored-by: Mm2PL <miau@mail.kotmisia.pl>

src/controllers/hotkeys/HotkeyController.cpp

@@ -4,9 +4,12 @@
 #include "controllers/hotkeys/Hotkey.hpp"
 #include "controllers/hotkeys/HotkeyCategory.hpp"
 #include "controllers/hotkeys/HotkeyModel.hpp"
-#include "singletons/Settings.hpp"
+#include "util/RapidJsonSerializeQString.hpp"  // IWYU pragma: keep
 
+#include <pajlada/settings.hpp>
+#include <QMessageBox>
 #include <QShortcut>
+#include <QWidget>
 
 namespace {
 

src/controllers/plugins/PluginController.hpp

@@ -13,16 +13,15 @@
 #    include <QString>
 #    include <sol/forward.hpp>
 
-#    include <algorithm>
 #    include <map>
 #    include <memory>
 #    include <utility>
-#    include <vector>
 
 struct lua_State;
 
 namespace chatterino {
 
+class Settings;
 class Paths;
 
 class PluginController