Add purchase details to transaction notes

'note' is not really good for this purpose. We can create an order in square (https://docs.connect.squareup.com/api/connect/v2#endpoint-createorder) that would hold the order items info. Then we can link this order to the transaction using the transaction's order_id parameter (https://docs.connect.squareup.com/api/connect/v2#endpoint-charge).

The patch creates a square order based on the DC order line items and links it to the square transaction.

The square order total is required to match the payment amount. This is not the case if we have order promotions or other adjustments.

Case #1 The square order total is more than the payment amount.
SInce square does not allow negative amounts for line items, we decrease square line item prices until we make up for the difference.

Case #2 The square order total is less than the payment amount.
We create a fake square line item with name 'Adjustments' to make up for the difference.

Would be nice if someone could test this with live transactions too: sandbox transactions do not appear on the dashboard, I could only check square orders via the api.

Instead of juggling with square line item base prices we should probably use square line item discounts
$line_item->setDiscounts($discounts)

Using square discounts now. Code is shorter and easier to read this way.

Reroll for latest dev.

focal55 have you given this a test in production? I'm going to do a basic test. But we need some end-user confidence before we commit and put in a release.

I reached out to Square to see if we can find additional ways to test beyond: 1) Push to API and see no errors. 2) Use API to pull order down and verify.

focal55, thanks! I'll commit this and then mark it for 7.x backport.

Committed to 8.x.

I don't like the "Patch (to be ported)" status. Let's close this as fixed and just have a new issue, #2931511: Backport "Add purchase details to transaction notes" to 7.x