Display secondary / billing address in checkout

[kieckhafer]

Feature Name

Secondary Address display in checkout

Summary description

When checking out a cart, we give you the option to use a second different address as a billing address for your payment method. Once you enter this information and move on to the next checkout step, your secondary address is no longer displayed anywhere in checkout, nor the order confirmation page:

In addition, any secondary address that is input should be saved for future use ( #415 )

Rationale for why this feature is necessary

A user should be able to visually confirm that they are using a different address for payment and shipping.

Expected use cases

Any time a user checks out with a payment method that requires a billing address.