Versioning in parameter models

[chrisiacovella]

Modelforge relies upon using pydantic models to define all the key parameters. As we have set it up, the pydantic models will throw an error if not all parameters are defined (and by marking extra="forbidden" we will also throw an error if additional parameters are provided), so we will automatically catch incompatibilities. But we should make it easier on ourselves by providing some versioning so that we can specify in every code release which version of the parameter models it is compatible with.

In this regard, it might make sense to take all the pydantic models and put them in their own submodule (e.g., modelforge.parameters) to make things a bit more self contained and be able to easily just include _version.py just for these.