Add ignoredProperties to DataRelease and add condition on relevant exceptions creation

1. Hardcoding of special logic for sphn:DataRelease such that the properties sphn:hasDataProviderInstitute and dct:conformsTo are added to the sh:ignoredProperties:

if nameOfClassElement == 'DataRelease':
            ignoredPropertyList = [RDF.type, URIRef(str(SPHN) + 'hasDataProviderInstitute'), DCTERMS.conformsTo)]
        else:
            ignoredPropertyList = [RDF.type]

We assume that the DataRelease concept is defined only for SPHN.

2. Add condition when defining relevant exception such that we add the element to the list only if it has not already been added:

if element not in relevantExceptions[element['property']]:
                    relevantExceptions[element['property']].append(element)