Average surface and volume derived quantities in Cylindrical and Spherical

[jhdark]

Proposed changes

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Types of changes

What types of changes does your code introduce to FESTIM?

• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Code refactoring
• [ ] Documentation Update (if none of the other choices apply)
• [ ] New tests

Checklist

• [ ] Black formatted
• [ ] Unit tests pass locally with my changes
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation (if appropriate)

Further comments

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.57%. Comparing base (282071e) to head (e747d52). Report is 26 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #820 +/- ## ======================================= Coverage 99.56% 99.57% ======================================= Files 61 61 Lines 2747 2796 +49 ======================================= + Hits 2735 2784 +49 Misses 12 12 ```

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