Support for referencing @interfaceObject without contributing a field

[aliosmanisikk]

It would be nice to have non-resolvable @interfaceObject to reference an interface without contributing a field. Similar to the regular Entities https://www.apollographql.com/docs/federation/entities/#referencing-an-entity-without-contributing-fields

// Subgraph A
interface Media @key(fields: "id") {
  id: ID!
  title: String!
}

type Book implements Media @key(fields: "id"){
  id: ID!
  title: String!
}

// Subgraph B
type Media @key(fields: "id", resolvable: false) @interfaceObject {
  id: ID!
}

type Query {
  numberOneMedia: Media!
}