Pre-calculate shipping costs for available addresses

[dandv]

Use case: the user has 2 or more address they can ship to. The merchant would like to pre-calculate the shipping costs and ideally pre-sort the addresses by cost.

To prevent accessing PII without the user's knowledge, the UA could provide only partial addresses (e.g. Country + zip/postal code) upfront, based on which the merchant could still calculate costs.

[ianbjacobs]

This issue was raised in Payment Request, but closed once we removed addresses from that API. We anticipate adding addresses back to the specification and so are re-opening this issue proactively.