rust harmonizer missing some implementations

[EverlastingBugstopper]

The Rust API Guidelines list a bunch of common traits that are eagerly implemented for most library types. I think we should implement most of these for ServiceDefinition (and maybe rename it SubgraphDefinition) so it's easier to work with in tests.

I'd love to do this:

        let actual_film_subgraph = subgraph_definitions.get(0).unwrap();
        let actual_people_subgraph = subgraph_definitions.get(1).unwrap();

        let expected_film_subgraph = SubgraphDefinition::new(
            "films",
            "https://films.example.com",
            "there is something here",
        );
        let expected_people_subgraph = SubgraphDefinition::new(
            "people",
            "https://people.example.com",
            "there is also something here",
        );

        assert_eq!(actual_film_subgraph.clone(), expected_film_subgraph);
        assert_eq!(actual_people_subgraph.clone(), expected_people_subgraph);

Unfortunately I can't seem to compare these two quite like this because ServiceDefinition does not implement Clone and either Eq or PartialEq... or at least I think that's why I can't do the above. I've got something working but would be nice to add these implementations for sure!

This is what I'm doing for now:

        assert_eq!(actual_film_subgraph.name, "films");
        assert_eq!(actual_film_subgraph.url, "https://films.example.com");
        assert_eq!(actual_film_subgraph.type_defs, "there is something here");
        assert_eq!(actual_people_subgraph.name, "people");
        assert_eq!(actual_people_subgraph.url, "https://people.example.com");
        assert_eq!(actual_people_subgraph.type_defs, "there is also something here");
        ```