20031: Preselect current collection in move/copy to existing collection tree picker

20031: Preselect current collection in move/copy to existing collection tree picker

* Add collection support to ancestor service
* Initialize copy/move to existing collection form with current collection
* Use initial form value and ancestor service to preload tree picker with initial selection
* Add refresh action to tree picker search actions to populate initial expanded tree picker items after preselection
* Allow pristine copy/move to existing form to be submitted with initial value (relies on form validation to disable submit if no initial value)

Arvados-DCO-1.1-Signed-off-by: Stephen Smith <stephen@curii.com>