spatially varying and consistent biogeochemistry

[kmdeck]

Purpose

The only parameters of the biogeochemsitry model which are spatially varying currently are those related to soil properties. This PR makes them spatially varying (i.e. supporting parameter fields), and it moves them to the "soil driver struct".

We then make the soil driver struct in the LandModel constructor using the soil parameters themselves, which enforces consistency

To-do

Content

• Move porosity, theta_a100, and b out of the SoilCO2 Parameters
• Move them into PrescribedMet, PrognosticMet (what we call the "soil driver" for Biogeochemistry)
• access them via the driver in the soil CO2 update aux function, rather than from params struct
• add check in integrated model constructor that they are the same - not needed, the constructor handles this.
• update tests

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• I have read and checked the items on the review checklist.

[AlexisRenchon]

I have read through.
I think this is great! Thank you!
I don't have comments for the PR (ok to merge), but we will talk about it in person