UI: Rename animation footers to Playback Controls

Rename the menu item "Footer" in Animation/VSE to "Playback Controls".

This only affects the menu item label under `View`, in the following editors:
* Dope Sheet
* Graph Editor
* NLA Editor
* Sequencer

The name "footer" has issues:

* It's not descriptive of what it does/contains.
* It can be moved to the top, so no longer a footer.
* When used in other editors, it may contain different things so it
  is unexpected what to find in it.

See PR for screenshots.

Pull Request: https://projects.blender.org/blender/blender/pulls/146727

scripts/startup/bl_ui/space_graph.py

@@ -213,7 +213,7 @@ class GRAPH_MT_view(Menu):
         layout.prop(st, "show_region_ui")
         layout.prop(st, "show_region_hud")
         layout.prop(st, "show_region_channels")
-        layout.prop(st, "show_region_footer")
+        layout.prop(st, "show_region_footer", text="Playback Controls")
         layout.separator()
 
         layout.operator("graph.view_selected")