Vertical tabs (#1815)

* Vertical tabs

* Vertical tab wrapping

* Fix formatting

* Cleanup code

* Updated changelog

* Hide button row if no buttons exist

* Fix tab width expansion

Co-authored-by: fourtf <tf.four@gmail.com>

src/singletons/Settings.hpp

@@ -9,6 +9,7 @@
 #include "controllers/highlights/HighlightPhrase.hpp"
 #include "controllers/moderationactions/ModerationAction.hpp"
 #include "singletons/Toasts.hpp"
+#include "widgets/Notebook.hpp"
 
 namespace chatterino {
 
@@ -78,6 +79,9 @@ public:
     BoolSetting colorizeNicknames = {"/appearance/messages/colorizeNicknames",
                                      false};
 
+    IntSetting tabDirection = {"/appearance/tabDirection",
+                               NotebookTabDirection::Horizontal};
+
     //    BoolSetting collapseLongMessages =
     //    {"/appearance/messages/collapseLongMessages", false};
     IntSetting collpseMessagesMinLines = {