Changes to Create custom field

removed the media type application/octet-stream from the request body

added the new link enum value to the items/type response property for the response status 200

added the new optional header request parameter x-organization-id

added the new optional query request parameter skipWebhook

added the new optional request property fields/items/required

added the new optional request property fields/items/unlisted

added the new enum value lineItemPurchaseOrders to the path request parameter entity

added the new enum value purchaseOrders to the path request parameter entity

added the new link enum value to the request property fields/items/type

added the non-success response with the status 403

added the non-success response with the status 404