CI code that produces the confusion matrix from episode 2 on 3 operating systems

[psteinb]

This closes #233

[psteinb]

This PR pulls in the cce app into the repo. I needed to fix a small bug in it and thought then I could include it straight away.

[psteinb]

Open question for me: should I try to find a way to either:

• create CI artifacts (the confusion matrices in a .txt file)
• or try to commit back the confusion matrix into the repo in any way.

Feedback welcome.

[dafnevk]

This PR pulls in the cce app into the repo. I needed to fix a small bug in it and thought then I could include it straight away.

Maybe this is fine for now, the cce tool does not have an actual release and is not very actively maintained. However, we may develop and maintain it further in the esciencecenter-digital-skills organization, then we don't want to maintain a copy.

[dafnevk]

Would your idea be to include the output of this action directly into the lesson material? Then I guess we need to

1. add a (hidden) line of code into the episode that writes a .png file
2. Have the CI commit the image back

Of course we can only include the output for one run one one OS in the final lesson.

[svenvanderburg]

Closing this PR as it is stale for over a year now.