externalize audits so they can be run locally and/or within target library CI/CD

### Story

As a GraphQL library maintainer I would like to be able to run HTTP spec audit locally to ensure my client/server remains compliant with the spec.

### Acceptance criteria

- GraphQL library maintainer is able to run HTTP spec audit locally

### Related

* https://github.com/graphql/graphql-http/issues/8
* [Apollo Federation Spec Compliance Tools](https://www.apollographql.com/blog/backend/testing/new-apollo-federation-spec-compliance-tools-for-graphql-server-maintainers/)