Add example in definition/__tests__ of all types working together

[dschafer]

The top level tests describes a pretty simple schema, but it doesn't go into input objects or unions. A more comprehensive example would be useful.

[ruslantalpa]

I needed a reference output for introspection feature in lua implementation so i created this simple example https://github.com/ruslantalpa/graphql-js/tree/tests_refactor/src/__tests__/todo
If @leebyron thinks it's worth developing (adding more properties showcasing different things like input objects, unions ...) and has some suggestions, i can work on it a bit more to make it PR worthy

[leebyron]

Awesome!

[JoviDeCroock]

Should be covered in https://github.com/graphql/graphql-js/blob/16.x.x/src/__tests__/starWarsSchema.ts