Add functionality to list all generators in instance

[vc1492a]

Add functionality to the Models() class that allows users to return a list of generator IDs in the Henosis instance, with or without associated information such the models used by the generator, its inputs and outputs, etc.

This functionality is not yet present in the API (GET generators) and a new endpoint should be created before including the API's results as part of the class call. This functionality would be nice to have as part of the Models() class as to include additional options and improve users' modeling workflow.