Add Dockerfile (and maybe pipelines for tests?)

[blueprismo]

Is your feature request related to a problem? Please describe.
No, I just love Docker :) 🐳

Describe the solution you'd like
Dependencies are minimal in this project, but why not having it dockerized and that way it will always work everywhere [with the same cpu-arch]? (and there will be no mismatches between versions (npm, node, OS running it...)).

I can contribute with a Dockerfile and some initial github actions workflow.

Additional context
None 💯

[skeddles]

If the docker file is completely optional, you are welcome to submit a pull request that adds one. I don't think it's really necessary since i think most of our modules are pure js, which should run the same on every platform. But if it helps some people without forcing them, then I'm for it.

[unsettledgames]

Implemented in #99