fix: allow for sameAs links

[sennierer]

To resolve the sameAs problem described in #819 we need to get the sameAs URIs defined in the RDF files. Other than originally thought not all of them are using owl:sameAs. This PR proposes another attribute in the toml definition that allows to set a sparql query that retrieves sameAs uris. Eg for Persons in Wikidata the definition could look like:

superclass = "apis_ontology.models.Person"
regex = "http://www.wikidata.org.*"
sameas = """
PREFIX wdtn: <http://www.wikidata.org/prop/direct-normalized/> 
PREFIX wdt: <http://www.wikidata.org/prop/direct/>
SELECT ?sameas ?parl_url
WHERE {
?subject wdtn:P227 ?sameas
OPTIONAL {
?subject wdt:P2280 ?parl_nr .
BIND(concat("https://www.parlament.gv.at/WWER/PAD_", str(?parl_nr)) AS ?parl_url)
}
}
"""
[[attributes]]
# name
sparql = """
PREFIX wdt: <http://www.wikidata.org/prop/direct/>
SELECT ?forename
WHERE {
  ?person wdt:P735/rdfs:label ?first_name .
  BIND(?first_name AS ?forename)
}
"""

This fetches the GND link and uses the Parlament Nr to create a link and returns that. As a fallback a query for owl:sameAs is used.
The PR also changes the RootObject to accept the sameas attribute retrieved via the sparql queries (or actually any list of uris) directly via putting them in the sameas attribute.

resolves #819

[sennierer]

I will fix the tests when we have finished discussing the proposed changes.