Remove old temperature and moisture dependance

[jacobcook1995]

Description

This PR removes a couple of functions that calculate the impact temperature and moisture have on soil processes, as they are not really relevant to the planned soil model. These are replaced by new functions to calculate the impact that temperature and soil water potential on specifically microbial rates.

I decided against removing the old moisture function entirely as this would involve changing how significant parts of the model works (e.g. sorption of organic matter to minerals). This change will instead come as part of a subsequent pull request that will make the model enzyme-explicit.

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

[vgro]

LGTM. I cannot say much about the science but it all looks sensible to me.

[davidorme]

LGTM

[codecov-commenter]

Codecov Report

Merging #325 (425331e) into develop (62f0612) will decrease coverage by 0.13%.
The diff coverage is 91.89%.

@@             Coverage Diff             @@
##           develop     #325      +/-   ##
===========================================
- Coverage    96.62%   96.50%   -0.13%     
===========================================
  Files           48       48              
  Lines         2400     2403       +3     
===========================================
  Hits          2319     2319              
- Misses          81       84       +3     

Files	Coverage Δ
virtual_rainforest/models/litter/constants.py	100.00% <ø> (ø)
virtual_rainforest/models/litter/litter_model.py	100.00% <ø> (ø)
virtual_rainforest/models/litter/litter_pools.py	100.00% <ø> (ø)
virtual_rainforest/models/soil/constants.py	100.00% <100.00%> (ø)
virtual_rainforest/models/soil/soil_model.py	100.00% <ø> (ø)
virtual_rainforest/models/soil/carbon.py	95.94% <82.35%> (-4.06%)	⬇️

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