Blender Git Loki

Bugfix [#28962] Changing actions via undo/delete all keyframes lacks UI refresh

Slightly hacky fix to get updates working for Action Editor header when there
are changes of the active action (via undo and/or deleting all keyframes at
once). Since the action referenced by the editor only gets updated when anim
channel filtering (e.g. as a result of the channel syncing operation) is
invoked. Added comments noting where these updates actually occur