Provide explicit search order triples

acdhOeaw\arche\lib\RepoDb::getPdoStatementBySqlQuery() now also generates triples providing explicit order of resources matching the search. This allows reliable reproduction of the search ordering on the client side (also by acdhOeaw\arche\lib\RepoDb::getResourcesBy*() and acdhOeaw\arche\lib\Repo::getResourcesBy*() methods).

The new config property $.schema.searchOrder is used to configure the property providing the order.