Automate testing across different cloud platforms + OS images

[christippett]

I'm thinking of creating a GitHub Action that'll deploy a VM + container to each cloud platform. The test could fire off a few requests as a health check against the instance's domain/endpoint which would provide assurance that Terraform and the cloud-init scripts are working properly and the functionality is consistent across different clouds and operating systems.

Hopefully this could be done while staying within the free tier for each platform.