Objectives:
* Split reference dialog (at least for now) an edit and an insert dialog
* Add reference search widget for selecting an existing source, or
choosing to add a new one
* Abstract reference names, don't allow editing them and generate them
when needed
* When editing groups, move the internal item and update all references
to it
* Resolve name conflicts when moving a reference to a new group by
generating a new list key
Bonus:
* Add getNodeGroups method to internal list
* Add getUniqueListKey method to internal list
* Add destroy functionality to ce.node to release events and references
Bug: 49733
Change-Id: Ib244ff6ad9b4cee1decfd9b9e1d3d4e9cdcfb78c
