[D-Req-V01-222] Implement text indexing in "dalia" dataset

RDF predicates for text indexing:

• learning resources:
  • dcterms:title
  • dcterms:description
  • schema:keywords
  • schema:name
  • schema:familyName
  • schema:givenName
• communities:
  • dcterms:title
  • dcterms:description