Dropbox poll function was not sufficiently checking compatibility, so we
could end up calling
`WM_drag_get_local_ID_or_import_from_asset`. The asset might not
actually be used because of further checks later (so it would end up as
an orphan which would go away after save/reload), but still the import
should be avoided.
This fixes the case for dropping a shader nodegroup to the Geometry
Nodes Editor by getting asset metadata (and checking if the nodetree
type matches editor) in the dropbox poll function.
Will check on other possible cases of drag-drop to incompatible editors
next.
Pull Request: https://projects.blender.org/blender/blender/pulls/111921
30e3caaf82