Adding unit conversions for precipitation amount and surface snow amount

[lauracasp]

Description

Adding unit conversions for precipitation amount and surface snow amount implementing the equivalence of kg * m^-2 (amount per area) and mm (thickness of the amount).

The conversion is needed for the climatic impact-drivers recipe.

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Checklist

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• 🧪 and 🛠 Documentation is available
• 🛠 Unit tests have been added
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.49%. Comparing base (b22d2bd) to head (f0e2a1d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3193      +/-   ##
==========================================
- Coverage   96.50%   96.49%   -0.02%     
==========================================
  Files         280      280              
  Lines       16282    16282              
==========================================
- Hits        15713    15711       -2     
- Misses        569      571       +2     

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[schlunma]

Thanks @lauracasp, looks great! Could you please add two lines of documentation and a very simple test? You can basically Copy-paste the changes from #3182 and slightly adapt them. Thanks so much!

[lauracasp]

@schlunma thanks for the reference! Should all be done now.

[schlunma]

Perfect! Please also mention it here, then this is good to go!

[schlunma]

One more thing I forgot: If you'd like, you can add yourself to the .zenodo.json and CITATION.cff files to get acknowledged as author 😊

[schlunma]

Closing and re-opening to get CLAassistant to run