Add a "Save" button for new address entry and refresh the payment method add form when it's submitted

#3583042: Refresh the payment method add form on existing address selection didn't address the case when a new address is entered, only when an existing address is selected from the address book widget.

For new address entry, we want to introduce a new "Save" button as implemented on a recent client project to explicitly require a save operation. We would then have a definite event against which to execute related logic while also reducing the saved address to plaintext representation instead of leaving it open as form elements.

The payment method add form would then use this save operation to refresh itself.