Changes to Preview usage events

the events/items/customer_id response's property type changed from object to string for status 200

the events/items/duplicate response's property type changed from object to boolean for status 200

the events/items/error/allOf[#/components/schemas/PreviewUsageEventErrorApiDto]/param response's property type changed from object to string for status 200

the events/items/event_id response's property type changed from object to string for status 200

endpoint added