Direct input from plant model to the litter model

[jacobcook1995]

Description

This PR changes the litter model to receive input from the plant model. This input then gets split between pools based on its lignin content and C:N ratio. Science wise it is relatively straightforward, but there's a couple of things to note from a code perspective:

1. @davidorme this PR alters plant model code, let me know if you are happy with the general structure
2. This PR adds 11 new variables to the data object, this has lead to some fairly huge functions signatures, if anyone has any suggestions for how best to handle this please let me know.

Type of change

• [x] 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

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

Further checks

• [x] Code is commented, particularly in hard-to-understand areas
• [x] 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 :white_check_mark:

Project coverage is 94.93%. Comparing base (fb253a5) to head (b8f44a4).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #509 +/- ## =========================================== + Coverage 94.90% 94.93% +0.03% =========================================== Files 71 73 +2 Lines 4020 4050 +30 =========================================== + Hits 3815 3845 +30 Misses 205 205 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.