Changes to Create a parcel line item

request property data/relationships/shipment_line_item reactivated

added the new required request property data/relationships/parcel/data

added the new required request property data/relationships/shipment_line_item/data

added the new required request property data/relationships/stock_line_item/data

request property data/type was restricted to a list of enum values

removed the request property data/attributes/sku_code

removed the request property data/relationships/parcel/id

removed the request property data/relationships/parcel/type

removed the request property data/relationships/shipment_line_item/id

removed the request property data/relationships/shipment_line_item/type

removed the request property data/relationships/stock_line_item/id

removed the request property data/relationships/stock_line_item/type

the type request property default value parcel_line_items was removed

added the new parcel_line_items enum value to the request property data/type

added the media type application/vnd.api+json for the response with the status 201