Extern: Entity.get_parents_recursively() does not work for unretrieved parents

extern: https://gitlab.com/caosdb/caosdb-pylib/-/issues/90

Entity.get_parents_recursively() does not work unless the full ancestry has been retrieved from the server.

• Write integration test
• Decide on solution
• Implement solution
  • caosdb-pyinttest!54 (merged)
  • !94 (merged)
• Followup issues created if necessary