UI: Add 'Channels' region toggle in animation editors

This way users can also assign shortcut to it or add it to quick favourites.

Pull Request: https://projects.blender.org/blender/blender/pulls/117837

scripts/startup/bl_ui/space_graph.py

@@ -148,6 +148,7 @@ class GRAPH_MT_view(Menu):
 
         layout.prop(st, "show_region_ui")
         layout.prop(st, "show_region_hud")
+        layout.prop(st, "show_region_channels")
         layout.separator()
 
         layout.operator("graph.view_selected")