Blender Git Loki

Outliner: Add object(s) to new collection

Suggested by Pablo Vazquez (venomgfx).

The idea here is that it should be easy to work in the outliner by picking a
bunch of objects and adding them to a new collection.
Where is the new collection? In the same level as the "outliner active" object.

Note, since the outliner has no pure concept of an active object, I'm using
the highlight tag for this. Hopefully it works fine.

It should work in "Collections", "View Layer", and "Groups".
Only when collections are not filtered out.