Feature ch-stats as a separate folder

[adrienmellot]

Fixes #313
Partial fix for #315

Co-authored by: Francesco Sanvito sanvitofrancesco@gmail.com

Checklist

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• CHANGELOG updated
• Minimal workflow tests pass
• Tests added to cover contribution
• Documentation updated
• Configuration schema updated

[sjpfenninger]

I've added a fix for the linux verison conflicts issue. The PR now builds for me successfully on linux-x86. @brynpickering @adrienmellot can you maybe do a check if this doesn't break on macOS in turn?

[timtroendle]

Thanks for the PR. This is a large PR that doesn't seem to add any feature as far as I can tell. Would it be possible to refactor this change to something that actually adds a feature or fixes a bug? Why not proving a fix for #291? It will be really difficult to review this without a clear purpose.

I understand this may be the wrong time and it may not be reasonable to refactor it now. In that case, let me know and I will start trying to review.

[adrienmellot]

Fair point. Initially the point for this PR was to move towards #315 gradually, by first including ch-stats and then including Eurostat processing separately, before finally merging both with the actual workflow. In the meantime other commits have piled up to solve environment issues on linux. As you point out this doesn't solve anything yet, and in the meantime #291 was solved separately.

[brynpickering]

@timtroendle: as @adrienmellot mentioned, this is part of a wider aim to split out data pre-processing based on source rather than sector. If we want (relatively) small PRs, we cannot expect every one to fit neatly into a feature or bug fix - some are simply refactoring or a step in the right direction towards an end goal. In this case, @adrienmellot has linked to an issue that describes the purpose of this PR and I have updated the comment to link to the meta issue.