Changes to List Messages

removed the enum value unread (is_read = false) from the property items/ of the query request parameter status[]

added the new failure_by_vendor enum value to the results/items/status response property for the response status 200

added the new unread enum value to the results/items/status response property for the response status 200

added the enum value unread (marked unread after being read unread_at later than read_at) to the property items/ of the query request parameter status[]

removed the delivery_failure enum value from the results/items/status response property for the response status 200

api path removed without deprecation

endpoint added