Adding fix for ORAS5

[jmalles]

Description

Fix for ORAS5. It includes the option to make the 'irregular' (2d) grid 'unstructured' (1d) and UGRID-compliant. To do so, one needs to add the extra facet 'make_unstructured: true' and/or 'ugrid: true' in the recipe.

The mesh description ('horizontal_grid' in the recipe) needs to be read from a file (oras5_mesh.zip), which is based on a file that can be downloaded here. Since ORAS5 data is on the ORCA025 (Arakawa-C grid), there are different mesh files for tracers (T), and zonal/meridional velocities (u/v).

An example recipe for ORAS5 can be found here.

Some already downloaded data are stored here:
/work/bd1083/b380216/extraobsraw/Tier2/ORAS5/single_level
/work/bd1083/b380216/extraobsraw/Tier2/ORAS5/all_levels
/work/bd1083/b382555/extraobsraw/Tier2/ORAS5/all_levels

The grid files are also stored on Levante:
/work/bd0854/b382555/extraobsraw/Tier2/ORAS5/grids

Link to documentation: tba

---

Before you get started

• ☝ Create an issue to discuss what you are going to do

Checklist

It is the responsibility of the author to make sure the pull request is ready to review. The icons indicate whether the item will be subject to the 🛠 Technical or 🧪 Scientific review.

• 🧪 The new functionality is relevant and scientifically sound
• 🛠 This pull request has a descriptive title and labels
• 🛠 Code is written according to the code quality guidelines
• 🧪 and 🛠 Documentation is available
• 🛠 Unit tests have been added
• 🛠 Changes are backward compatible
• 🛠 Any changed dependencies have been added or removed correctly
• 🛠 The list of authors is up to date
• 🛠 All checks below this pull request were successful

---

To help with the number pull requests:

• 🙏 We kindly ask you to review two other open pull requests in this repository

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 186 lines in your changes missing coverage. Please review.

Project coverage is 93.81%. Comparing base (31fe0d4) to head (013b219).
Report is 69 commits behind head on main.

Files with missing lines	Patch %	Lines
esmvalcore/cmor/_fixes/oras5/oras5.py	0.00%	130 Missing ⚠️
esmvalcore/cmor/_fixes/oras5/_base_fixes.py	0.00%	56 Missing ⚠️

❌ Your patch check has failed because the patch coverage (0.00%) is below the target coverage (100.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2422      +/-   ##
==========================================
- Coverage   94.99%   93.81%   -1.18%     
==========================================
  Files         255      257       +2     
  Lines       14793    14979     +186     
==========================================
  Hits        14052    14052              
- Misses        741      927     +186     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[bettina-gier]

Tried with the example recipe and it looks good, output seems as expected. Fast look through the code looks good. I'll do a more detailed review when I have more time.

[schlunma]

Hi @jmalles, thanks for contributing!

To start the review process and finalize this, we need tests (see e.g., here) and some documentation (see e.g, here). Thanks!!