Creates a checking Bakkt bank account for the user (session or user-uuid). Checking accounts support deposits from 1st and 3rd party senders.

Optionally issues a physical (plastic) debit card together with the account via request_physical_card. This option is available only for a specific (special) merchant and only on checking accounts; the savings and trading endpoints reject it with a 400. If the fiat provider resolved for the user cannot issue cards, the request fails and no account is created.