[workflows] reorg

[kwk]

• The python-format-and-tests.yml workflow did too many jobs in one workflow and didn't allow us to treat each job it did with different care.

• We want code to be formatted with black and we want this to be mandatory in code reviews. Let's do this in check-python-code-formatting-with-black.yml from now on.

• We want python tests to pass, so let's do this in check-python-code-with-pytest.yml.

• We want to generate coverage but we potentially don't want to make this mandatory for pull requests. For example, see
  
  for this PR which doesn't change anything regarding coverage numbers. See check-python-code-coverage.yml.

• The retest.yml just got a new name: retest-chroots-on-testing-farm.yml.

• The Makefile got dedicated target we can use from within the workflows.

In order to unblock this PR I first have to get approval for it and then I can tune the branch protection settings to no longer require these old workflows but the new ones

[tuliom]

We want code to be formatted with black and we want this to be mandatory in code reviews.

I don't remember ever discussing this part with the rest of the team. IMHO, it's a good idea to have a tool that helps to check code formatting, but I've seen this test fail with super-strict results, e.g. complaining about how the lines of imports should be organized/grouped together.

Is it possible to reduce that requirement?

[tuliom]

There are 2 tests pending (run-tests and check-python-with-black).
Does this PR need to be merged before these tests are executed?

[kwk]

We want code to be formatted with black and we want this to be mandatory in code reviews.

I don't remember ever discussing this part with the rest of the team. IMHO, it's a good idea to have a tool that helps to check code formatting, but I've seen this test fail with super-strict results, e.g. complaining about how the lines of imports should be organized/grouped together.

Actually, the pre-commit git hook which should run on every git commit locally will complain about unordered imports etc. and reformat it to match the expectation. I've introduced black probably years ago to not have discussions about any formatting whatsoever.

Is it possible to reduce that requirement?

IMHO. No because I don't see why not to follow the idea that black has. I treat it as a replacement for what the go community has with their formatting.

[kwk]

There are 2 tests pending (run-tests and check-python-with-black). Does this PR need to be merged before these tests are executed?

The two pending tests are the ones, that I've split up in this PR:

1. check-python-with-black is now here.
2. run-tests is now here and here.

When this PR gets approved I'm going to adjust the branch protection rule to remove the two tests and instead add the pytest run and black formatting individually. At least that was the plan.

[tuliom]

While I disagree about the code style and I believe it should be relaxed, I have to recognize this PR is not changing the current behavior.
So, LGTM.

[kwk]

The branch protection rules for main are now changed to this:

Unfortunately the old branch protection way of configuring things only shows the job names and not the workflow names. black and pytest are the correct ones to choose though.

In the future we might wanna look into rulesets.