Blender Git Loki

Make Single User: support object data animation

In addition to _object_ animation, now _object data_ (mesh, curve, ...)
animation can now be made single user as well.

This came up in T89369 and while it is possible to do this via the
Outliner [where all actions have to be selected individually], this
seems to be more convenient to be done from the 3DView.

note: usercount of the action is checked now, if it single-user already,
no copy takes place (same thing could/should be done for
single_object_action_users as well).

note2: obdata is made single user as well (otherwise duplicated actions
will be assigned to the same shared obdata - which does not result in
unique animadata which is what we are after here)

ref. T89369

Maniphest Tasks: T89369

Differential Revision: https://developer.blender.org/D11683