Handle bundled shipping and static pricing

[helgatheviking]

The step container works quite well when the child items are shipped individually and the container price is priced-individually. However, I've recently had 2 folks who want to have (for example) 18 options resolve into 3 boxes of 6. Meaning you can buy as many multiples of 6 as you want, but you keep adding boxes to the price and to the shipping cost.

There's a possibility to maybe link the step quantity to the shipping dimensions. I think this will be tricky in 2 places.... 1. counting the product 18 item container as 3 line items in the shipping package. And then 2. splitting the items (whose weights get aggregated into the container box) semi-evenly into the different boxes.

I'm noting this, but I'm not sure we should do anything about it as if you want to sell unlimited boxes of 6, you should maybe not use the step counter and just have the customer keep adding boxes with different configs. This handles the above 2 problems with no additional work, even if it may or may not be less intuitive for the customer.