Test Unzip Step

[reimic]

What does this PR do?

• Adds tests for the the UnzipStep.
• Refactors the UnzipStepRunner to require a progress tracker and handle extraxt_to_path in both relative and absolute form.
• Downgrades code where necessary to properly function for all PHP versions >= 7.4.
• Adds test resources. (For now in the Step directory - TBD where test resources will be stored.)
• Takes care of a TODO by canonicalizing a path in the zip_extract_to function.

[reimic]

This is very interesting and proves the usefulness of a matrix test step. My local environment is set to PHP 7.4 and when I run those tests they pass without issue. But they do fail here. This is critical info and I am glad it is there. (Someone really wise must've implemented it.)

[reimic]

This PR became more about downgrading PHP than testing the Unzip Step. But that is a good thing, as downgrading the code becomes a priority. As a bonus - the matrix proved its usefulness.

[adamziel]

src/WordPress/Blueprints/Model/DataClass/UnzipStep.php is autogenerated, let's revert all the changes applied to it.