Blender Git Loki

Library Overrides: Don't move collections to Scene Collection when overriding

When using the "Make Library Override" operator on instance collections, keep
the overriden collection in the parent collection of the instance empty.
Previoulsy the collection would be added to the scene collection, which was
confusing and not what users expected. It was placed there for a reason after
all.

Part of T76555.

Reviewed by: Andy Goralczyk, Bastien Montange.

Differential Revision: https://developer.blender.org/D7626