Allow querying completed and expired receivers (incoming payments)

[mkurapov]

Context

In our backend GraphQL Admin API, we have a receiver query. It allows fetching a "local" incoming payment or a remote incoming payment, which is fetched at a different Rafiki instance using Open Payments.

Currently, the receiver query returns a payment only if it hasn't been completed yet. This is not the intended behaviour.

Expected behaviour

We should be able to fetch a receiver (local or remote incoming payment), even if it has already been completed.

The logic that needs to be changed is in the Receiver class, as we do not allow constructing a new Receiver instance from a payment that has been completed, expired, or has an empty methods array. We need to move those checks from inside the constructor directly to the places where they are needed (like during quote creation or outgoing payment processing).

Todos

• Allow creating Receiver instances even if the payment is completed, expired, or has an empty methods array
• Move those checks to the correct places where they are needed
• Make sure the receiver Admin API query returns incoming payments even if they are completed or expired