Bug fixes and testing for Stoichiometry

[sallymatson]

Description

1. Various bug fixes and improvements for stoichiometry:

• Fix the symbiote carbon supply calculations
• Fix the deficit calculation (everything is CX ratio - so need to divide carbon by ratio to get the other element value)
• Rename reclaim_ratio to turnover_ratio in FoliageTissue, to match the input which is passed through PFT extra traits as senesced leaf CN/CP ratios. This simplifies the foliage turnover, because now it's just the same calculation as others but using the turnover_ratio.
• Add error handling for distribute_deficit and distrubte_surplus so they can only be called when the element_surplus is positive or negative respectively.
• Simplify the calculations for distributing surplus and deficit for clarity and correctness.

2. Testing suite for all Stoichiometry classes

• These tests are now more validated for correctness, with clarity in the tests themselves for the logic and the calculations.

Fixes # (issue)

Type of change

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist

• Make sure you've run the pre-commit checks: $ pre-commit run -a
• All tests pass: $ poetry run pytest

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works
• Relevant documentation reviewed and updated

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.25%. Comparing base (8ce7bdf) to head (7acfa08).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1052      +/-   ##
===========================================
- Coverage    95.26%   95.25%   -0.01%     
===========================================
  Files           81       81              
  Lines         6887     6895       +8     
===========================================
+ Hits          6561     6568       +7     
- Misses         326      327       +1     

☔ 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.

[davidorme]

This is great - well structured and commented and very thorough.

I do have some big picture ideas on the test structure - just to make them a little more canonical / cleaner - which I think would be good to do. They're not blockers though.