As a Dev I want to return a list of all the event registrations of a giving organizer id

Acceptance criteria:

• Must return an array of event registration with the fields

[
   {
      event_id,
      event_name
    }
]

• If no event registrations was found return an empty array

Note: We may want to add the event creator field back to the campaign_events table. Denormalization here could make the query faster.