[DS-2195] importing AIPs with DSpace:master throws an NPE

https://jira.duraspace.org/browse/DS-2195

DatabaseManager.querySingle returns an untyped TableRow.  We can't use
querySingleTable because the row contains columns not found in the
required type.  Just force the row to have a type anyway, since it
does contain all of the columns required for that type.  Otherwise the
Group is not update()able.