ENH: add resolve_value to Property

https://gitlab.com/caosdb/caosdb-pylib/-/merge_requests/64

unittests/test_apiutils.py

@@ -72,10 +72,8 @@ def test_id_query():
 
 def test_resolve_reference():
     original_retrieve_entity_with_id = caosdb.apiutils.retrieve_entity_with_id
-
-    def dummy_entity(eid):
-        return db.Record(id=eid)
-    caosdb.apiutils.retrieve_entity_with_id = dummy_entity
+    caosdb.apiutils.retrieve_entity_with_id = lambda eid: db.Record(id=eid)
+    
     prop = db.Property(id=1, datatype=db.REFERENCE, value=100)
     prop.is_valid = lambda: True
     items = [200, 300, 400]