Replace tests by unittests

[paulzierep]

Since we cannot use the current tests for PR testing (github does not allow using the API keys - and we also should not do that).
We should replace the current test framework: https://github.com/galaxyproject/galaxy_codex/blob/main/.github/workflows/run_tests.yaml
With mocked unittests (mocking the API calls) like: https://github.com/galaxyproject/galaxy_codex/tree/main/sources/bin/tests
Once we have a good code coverage we can only rely on the unittests.
Currently we got:

Name                              Stmts   Miss  Cover
-----------------------------------------------------
bin/extract_galaxy_tools.py         515    425    17%
bin/extract_galaxy_workflows.py     300    197    34%
bin/shared.py                        75     34    55%
-----------------------------------------------------
TOTAL                               890    656    26%

Check with:

PYTHONPATH=bin coverage run -m unittest discover -s bin/tests
coverage report --omit="bin/tests/*"

Should we add the code coverage in the CI ?

[bebatut]

Yes, it would be nice to have the code coverage in the CI

[paulzierep]

#357