Switch Automated Tests to GitHub Actions

[joshuapease]

Overview

• https://github.com/vigetlabs/craft-viget-base/issues/83

This PR does the following:

• Switch from Circle CI to GitHub Actions
• Switch from docker-composer to DDEV (for local test runs and composer installs)

[nevinsm]

@joshuapease The only thing I am seeing missing in this would be updated docs