Create Wikidata agent as core module

[jravenel]

Create a wikidata agent on top of the Wikidata (wikipedia graph, and more) as core module.
The agent should be able to use the SPARQL queries in example and create new ones dynamically (to be researched)

[jravenel]

Example that works in

SELECT ?item ?itemLabel ?itemDescription WHERE {
  SERVICE wikibase:mwapi {
    bd:serviceParam wikibase:endpoint "www.wikidata.org";
                    wikibase:api "EntitySearch";
                    mwapi:search "Ontology";
                    mwapi:language "en".
    ?item wikibase:apiOutputItem mwapi:item.
  }
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
LIMIT 10