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

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

src/widgets/NotebookEnums.hpp

@@ -0,0 +1,16 @@
+#pragma once
+
+namespace chatterino {
+
+enum NotebookTabLocation { Top = 0, Left = 1, Right = 2, Bottom = 3 };
+
+// Controls the visibility of tabs in this notebook
+enum NotebookTabVisibility : int {
+    // Show all tabs
+    AllTabs = 0,
+
+    // Only show tabs containing splits that are live
+    LiveOnly = 1,
+};
+
+}  // namespace chatterino