Build endpoint to list training models

We need a new endpoint named ListModels that will list all training.Model available to the connected user.

The serializer must expose:

• model ID
• model name
• number of model versions:
  • all versions for admin or contributor
  • only versions with state = available AND tag is set for guests

The queryset must order the models by their name

An optional query filter named name must allow the user to filter the models by their name (using django filter name__icontains)