Break CI chunks into action steps

[chapulina]

GitHub action jobs can be run in several steps which can be collapsed when looking at the results, so it would be nice if this action could also be broken into various steps.

However, I couldn't find a good way to separate steps for a docker action like this one. So:

• Either there's something that can be called from within the docker file to start a new step but I haven't found
• Or there may be a nice way to create docker files that can be run in a chain (?)
• Or we could refactor this action to use something other than docker

[scpeters]

it looks like dart is able to use a docker container across multiple steps with a docker build, then docker run -itd which detaches the container and keeps it running, and uses subsequent calls to docker exec for the additional steps

[scpeters]

sorry, meant to include a link: https://github.com/dartsim/dart/blob/master/.github/workflows/ccpp.yml#L20-L33

[chapulina]

Nice! I see they're not using the Docker actions (using: 'docker'), but that's fine. I can look into this later this week.