[fix] sorting by name sub-attribute breaks the result list (#251)

This was caused by Hibernate adding an implicit join for the `scim_name` table when sorting by a `Name` sub-attribute. Unfortunately, Hibernate makes this a `CROSS JOIN` with a `WHERE` clause for filtering non-matching rows. Fixed this by explicitly adding a `LEFT JOIN` if and only if the client request an ordering by a `Name` sub-attribute.