We extend the logic of "seda.doref.del" hook so that it not only handles
the case of "simplified profile" but also the case of archive unit not
related to a profile. In the later case, we check that the container of
"SEDABinaryDataObject" is really a "SEDAArchiveUnit" (not sure what else
it could be) and trigger the operation deleting the binary data-object
when its parent object reference (SEDADataObjectReference entity) is
deleted.

Accordingly, we rename hook and operation classes and update their
docstring.

This resolves CONSEJIRA-643 but making deletion of an archive unit
containing a binary data object but not related to profile. New test
goes into test_schema.py below other tests related to the hook we
modified.