Link/append code needs proper access to scene/view3d data to handle
collections/objects instantiation.
Note that this is a temporary hack more than a proper fix, which would require
a deeper redesign of drag&drop code.
Also note that this will not handle 'properly' (i.e. as user would
expect it) cases like implicitely appended parent objects, in that only
the explicitely appended object will be dropped to the nes location, the
others will remain at their original coordinates.
Differential Revision: https://developer.blender.org/D12696
df9120b365