Guardian.Plug.LoadResource
Fetches the resource specified in a set of claims.
The Guardian.serializer/0 is used once the subject is extracted from the token.
The resource becomes available at Guardian.Plug.current_resource(conn) if successful.
If there is no valid JWT in the request so far (Guardian.Plug.VerifySession / Guardian.Plug.VerifyAuthorization) did not find a valid token then nothing will occur, and the Guardian.Plug.current_resource/1 will be nil