Fix loading packed scene with editable children at runtime
Fix loading packed scene with editable children at runtime

At runtime, packed scenes with nodes marked as editable instance where
saved with node type tags, which prevented the scene to be then loaded
as an instance, causing duplicated nodes in the tree.

This change ensures nodes marked as editable instances and their owned
children are properly set as instances.

That doesn't make a difference in the editor, since such nodes where
already set as instances based on their instance state, but it helps
at runtime where instance states are disabled.

Co-authored-by: latorril <1976b2482db9846b114c694d860125afb2734d3f@gmail.com>
(cherry picked from commit fab88a810ccd32ed5a573050171d12c73f69a668)

ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot