Migrate CI to Github Actions

[akhenry]

Summary

Currently we are utilizing a third party service (Circle CI) for our continuous integration workflows. This configuration predates the availability of GitHub Actions.

We should migrate to GitHub Actions for two reasons:

1. It allows us to re-enable CI builds for open-source contributors because GitHub offers the option of only running CI workflows for external contributors with the permission of a Team member.
2. It simplifies our CI configuration by standardizing on a single service.
3. It gets us off a commercial third-party service