bugfix: schemas/vegbien.sql: locationevent: locationevent_unique_within_creator unique index on sourceaccessioncode: need to add stratum_id, because the addition of stratum_id to this table instead of a separate stratum_event table (which would have required more schema changes) means we need to use the awkward construction of appending stratum_id to every unique constraint, including ones that ordinarily would just pass through the datasource's pkey