feat: allow a location to be within multiple other locations

Due to the restriction that an organisation can have only 1
location (nl. werkingsgebied) we need to create ad-hoc locations containing
multiple locations. As such enforcing that a location can only be contained in a
single other location is too restrictive. For example, this would prevent the
same municipality location to be within two (or more) different locations for
different organisations.

config/resources/domain.json

@@ -945,7 +945,7 @@
         "located-within": {
           "predicate": "geo:sfWithin",
           "target": "locations",
-          "cardinality": "one"
+          "cardinality": "many"
         },
         "locations": {
           "predicate": "geo:sfWithin",