Create Product & SKU

Adding a new Product involves creating both a Product Item and a SKU Item, since a Product Item has to have, at minimum, a SKU Item. To create a new Product with multiple SKUs, you must: - Create the Product and Default SKU using this endpoint, making sure to add `sku-properties` in the product data. - You can't add `sku-values` to the SKU yet, since there are no enum IDs created yet. When this endpoint returns, it will have IDs filled in for the `sku-properties` enums. - With those IDs, update the default SKU with valid `sku-values` and create any additional SKUs (if needed), with valid `sku-values`. - You can also create the Product without `sku-properties` and add them in later. - If you add any `sku` properties, the default SKU will default to the first value of each option. Upon creation, the default product type will be `Advanced`. The product type is used to determine which Product and SKU fields are shown to users in the `Designer` and the `Editor`. Setting it to `Advanced` ensures that all Product and SKU fields will be shown. The product type can be edited in the `Designer` or the `Editor`.