CirrusSearch defines its own EntitySearch callback and we don't want to change it, because that's the point of allowing other places to override services.

Two ideas how to go around that:

1. EntitySearchHelperCallbacks in ServiceWiring will return a combined search helper with an existing EntitySearchHelper for property and ApiEntitySearchHelper if feddy props is enabled.
2. Wrap TypeDispatchingEntitySearchHelper in a service that dispatches either to the inner TypeDispatchingEntitySearchHelper or to a combined search helper with an existing EntitySearchHelper for property

We think 2) is better because it allows us to gradually change all places where we want search to work with federated properties.

Using "loc" as a search term finds the (only) local Property with the label "local prop", as well as a bunch of matching Properties on beta: https://wikidata-federated-properties.wmflabs.org/w/api.php?action=wbsearchentities&type=property&language=en&search=loc

Verified