401 status code for token authentication

I think in the case of token authentication, it would make sense to be able to return a 401, **even if** only one field errors out this way (referring to the example given in the original post). This status code is necessary to make this library compatible with authMiddleware in [React Relay Network Modern](https://github.com/relay-tools/react-relay-network-modern), which expects a 401 status code to refresh tokens.

_Originally posted by @berkcoker in https://github.com/graphql-python/graphene/issues/946#issuecomment-698617718_

Start by reading the linked original issue and the React Relay Network Modern authMiddleware requirement. Trace the token-authentication error path in Graphene to determine how a 401 could apply when one field errors. Done means the behavior is implemented with regression coverage and remains compatible with normal GraphQL error responses.

Escrito por el modelo de indexación a partir del texto del issue.