Acceptance criteria
- The "Enable an event registration" endpoint should accept a new field to specify the topics of the event.
- The "Edit an event registration" endpoint should accept a new field to specify the topics of the event.
- The "Get details of an event" endpoint response should include the topics of the event.
- Feature parity with Special:EnableEventRegistration, Special:EditEventRegistration, and Special:EventDetails respectively.
- The API documentation must be updated