Add CarboScope cmorizer

[bettina-gier]

Description

Adds Cmorizer for Jena CarboScope reanalysis, adding monthly fgco2 and nbp, along with their respective fx files.
I've added a downloader for the 2020 version, which I used for my paper, and tested the 2024 version to also run with the cmorizer, but without the downloader as I didn't get a good link for direct download for the respective file. The changes to add versioning detailed in #3452 don't seem to be implemented yet, how would you like to handle both versions for this cmorizer?

P.S.: original code from @schlunma , I just adapted it to the current ESMValTool version, can we add a coauthorship for him? 😃

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Checklist

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New or updated data reformatting script

• 🛠 Documentation is available
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• 🛠 The dataset has been added to the shared data pools of DKRZ and Jasmin by the @ESMValGroup/OBS-maintainers team
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[schlunma]

As a coauthor on this I probably shouldn't review it, but I am happy to have a final check and merge this once approved 😅