Change all core models from pydantic models to classes

[robcxyz]

Core models (ie context, input, source, data, hooks, path) into classes. No need for pydantic here.

Perhaps keep it in models and pull out hook models into own file. Also might be a good place to put in methods that help set each of these objects.

Should be done after #177

[robcxyz]

Changing this yielded a massive improvement in startup time since now each hook doesn't have to import pydantic. After 177, we should have reasonable startup times