BUG: Fix RemoveHierarchyChildrenNodes to send correct ChildNodeRemovedEvent

See #3854

This commit udpates the method so that the event "ChildNodeRemovedEvent"
is send for each child that has been removed. It also associate the
appropriate call data.

Thanks to "Nicole Aucoin <nicole@bwh.harvard.edu>" and
"Csaba Pinter <csaba.pinter@queensu.ca>" for reviewing the associated
changes.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23718 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Associate ChildNodeRemovedEvent with RemoveAllHierarchyChildrenNodes

See #3854

This commit ensure the event "ChildNodeRemovedEvent" is invoked
for each child removed using the method RemoveAllHierarchyChildrenNodes.

Thanks to "Nicole Aucoin <nicole@bwh.harvard.edu>" and
"Csaba Pinter <csaba.pinter@queensu.ca>" for reviewing the associated
changes.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23719 3bd1e089-480b-0410-8dfb-8563597acbee