Add GHA to build, test and publish the controller image

[tsurai]

This pull request features new build and test logic for the indy node controller as well as a general rework of the github actions pipeline separating it into four distinct parts: setup, build, test, push. A small amount of repetition had to be introduced in order to get a clean logical seperation.

Fixes #49

[mgmgwi]

Thanks @tsurai - looking good to me.

Question: We are mixing different OS images for node and controller during the test. While this probably will work fine, I don't think someone will run this in a production environment. So we should decide whether we want to test

• only matching OS versions (e.g. Ubunutu 18)
• the combination
• or if we want to create matching controller images

Any changes (if at all) should be done in another PR.

Thanks for contributing.

[mgmgwi]

@Echsecutor I think you need to modify the merge checks, because some actions have different names now.

[tsurai]

@mgmgwi The controller image only uses a tiny subset of libindy, namely just a few constants which are being installed via pip making it OS agnostic. It shares the lo interface with its node, listening only on localhost to not expose it to anything else on the same docker network. For all intents and purposes there is no functional difference between the different OS.
At the same time the dependency on podman rules out older OS like Ubuntu 16.

[mgmgwi]

Thanks for clarifying. I created #51 so we can discuss further actions in the next weekly meeting. I think larger companies have policies which OS they can use. I assume if they would run a Debian Indy Node they would most likely want to run the controller as well based on Debian.