The tests worked fine on multiple architectures, but would only run "bare metal", i.e. tests that required containers could not be run.
Enable basic multi-architecture support by allowing containers to be built using whatever architecture the host supports. Also allow cached containers to be defined for multiple architectures in container.yaml.
Add a Dockerfile which can be used as a container for other containers to provide a consistent development environment.
The primary goal is to allow development on Mac M1 but other architectures should find these improvements useful.
