added index on hash of uri column to support caom2_isPublic and caom2_getAuth lookup
added index on hash of uri column to support caom2_isPublic and caom2_getAuth lookup

opencadc/caom2db,esdc-esac-esa-int/caom2db,pdowler/caom2db,opencadc/caom2db,pdowler/caom2db,esdc-esac-esa-int/caom2db