Sort out type of constants argument in microclimate.py

[vgro]

At the moment, the type for constants in the microclimate submodule is set to AbioticSimpleConsts which is not general enough and makes it very clunky to use the function in a different model (it is used in the setup of the mechanistic abiotic model).

As soon as we solved the issues #162, #208, #342 and others on where to move which constants and how to call them, this needs to be changed accordingly.

[davidorme]

Over in #364, we've suggested using meta constants classes as a way of sharing constants among multiple models and which can be used to resolve this issue.