3D edit view should now update correctly when 3D Nodes and View3D
items are added, removed, or reparented in the scene.
Deleting the active scene will change the active scene to another
existing scene.
Fixes: QDS-1591
Change-Id: Ib885453574e72f486a236264cc10d88cb872e9c7
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>