This endpoint allows for the exchange of a one-time token & buyerID for an unverified buyer JWT. This enables Auth service to facilitate a hand-off between an external system and Bread.
This endpoint will lookup the one-time token using the provided UUID, and it will verify that the provided buyerID matches the buyerID associated with the one-time token.
For more information on how to generate a one-time token, refer to documentation on the
POST /auth/buyer/token/onetime endpoint.