Support for the Relay spec and Node interface

[smyrick]

Relay Spec: https://relay.dev/docs/guides/graphql-server-specification

There have been other discussions on how to support the Node Global ID interface in Federation: apollographql/federation#1067

We also have a related issue about a "simple" approach here: #168

The questions and problems come from where does the global Query.node interface resolver live? This could be defined in only one subgraph but ideally all subgraphs could use this as an entry point.

I don't have any proposal right now so this can serve as a generic feedback issue for the community