Get a signed token on behalf of the requesting DID for the requested service.

*This endpoint is part of the atproto PDS server and account management APIs. Requests often require authentication and are made directly to the user's own PDS instance.* *To learn more about calling atproto API endpoints like this one, see the [API Hosts and Auth](/docs/advanced-guides/api-directory) guide.* Get a signed token on behalf of the requesting DID for the requested service.