Update validateCartItems to use Stripe V2 format

Problem

use-shopping-cart was made with the SKU API in mind. We need to deprecate SKU within USC, and provide the required object structure for Stripe V2 session IDs.

Also need to make sure we are backwards compatible with the SKU API.

Work Required

• Scrub sku from the library in favor of id.

Sku is also used to describe the entire product in some places. In those places it should just say item. I would like to use product but Stripe has a whole Product API, don’t want to confuse that.

• Make sure validateCartItems and getCheckoutData use the appropriate format for creating sessions with Stripe V2

Should probably have some kind of conditional for sku so that if sku exists, use the current function we have set up.

Details on how V2 should be here: https://stripe.com/docs/api/checkout/sessions/create

[dayhaysoos]

Just FYI, the Stripe SKU API will continue to be deprecated, but sku is going to come back as a value. Not sure what kind of issues will arise there, but we’ll see!

[andria-dev]

I think we just need to finish scrubbing sku from the library and then we should be able to close this.