Changes to Create an activity. Roles: admin.

added the new optional request property managerAudienceId

added the optional property content/managerAudienceId to the response with the 200 status

the questions/items/externalReferenceId request property's maxLength was decreased to 255

added the optional property error/errorId to the response with the 400 status

added the optional property error/errorId to the response with the 401 status

added the optional property error/errorId to the response with the 403 status

added the optional property error/errorId to the response with the 404 status

added the optional property error/errorId to the response with the 500 status