Add field for `Components.modelCard.baseModel`

[bardenstein]

Proposal Base (aka foundation) models are one of the most important pieces of information to know about a given model, according to our research with dozens of AI/ML practitioners. Knowing whether a model is based on Llama2 or Stable-DIffusion or an unknown model that is worth investigating further before determining whether one can trust the current model.

Details FieldName: Components.modelCard.baseModel FieldType: List. Contains sub-fields Name, Version, and Source. Required: Yes

Example snippet

"modelCard" : [
       "baseModel": [
                "name": "Stable-diffusion-base",
                "version": "x1",
                "source": "https://huggingface.co/models/stable-diffusion-base-x1"
        ]
  ]

[stevespringett]

How does the base model use case differ from the parent model use case as described in #342?

Why would a base model be required?