Add support for additional query to always pull in fragments when source=="sparql"

[tdiepenbrock]

Sparql queries frequently need to pull in fragments from managed ontology triples stored under the /triplestore/ directory in the database. The current implementation forces these triples to be excluded whenever a geospatial query is submitted in the request, which is almost almost always. The idea is to add an additional query field at the datasource level that would contain a query that would always be combined with the usual bounding query in a cts.orQuery():

let additionalOrQuery = datasource.additionalOrQuery != null ? datasource.additionalOrQuery : cts.falseQuery();
//datasource.additionalOrQuery is some query, possibly a cts.directoryQuery("/triplestore/", "infinity")

let finalBoundingQuery = cts.orQuery(boundingQuery, additionalOrQuery);
//...on with the rest of building the plan