[pay] render additional information from payment link configuration

[soltoshi]

The merchant should be able to collect some information as part of fulfillment.

• email
• shipping address
• phone number

This can be stored on the payment link model as a map collect_details

interface CollectDetails {
  email: boolean;
  shipping_address: boolean;
  phone: boolean;
}

these values should default to false. The merchant will have a chance to determine whether these are collected when creating the payment link from a selector (dropdown or stack).