If a non-instanced collection is linked, any collection exporters on the
linked collection would be active and invokable. This is probably not
desired as it could inadvertently overwrite files from the original.
Disable the operators in this case.
See PR for how each of the various append/link scenarios behave.
Pull Request: https://projects.blender.org/blender/blender/pulls/123149
9d8a90d53c