Consider Codesandbox CI for this repo

We've found [Codesandbox CI](https://codesandbox.io/docs/ci) to be pretty handy, allowing contributors to `yarn add <>` a version of a graphql-tools package derived from a PR (effectively a simple forking solution).

Check out the comment on this PR for an example: https://github.com/apollographql/apollo-server/pull/6154

Start with the Codesandbox CI documentation and the example in Apollo Server PR #6154. Determine how this repository could expose PR-derived graphql-tools packages through that workflow, then define a contributor-verifiable integration and its completion criteria.

Written by the indexing model from the issue text.