Hugging Face Api for self-downloadable model

[aditya0by0]

Closes ChEB-AI/python-chebai#94

[aditya0by0]

We need to upload the models to chebai hugging face repo and update here

[aditya0by0]

The api has been updated for ensemble please check

[sfluegel05]

I merged the dev branch into this branch and was able to download the electra model from huggingface. I also created a config file (configs/huggingace_config.yml) based on my understanding of how to do that.

Some comments:

• api is a separate directory with its own cli - is there a reason for that or can we put that under chebifier?
• The api_registry.yml defines all the parameters for downloading the huggingface model. Can I refer to that from my config file (e.g. configs/huggingace_config.yml) with just the key of the model?
• In hugging_face.py, a dictionary is returned which matches the keys expected by the ensemble (e.g. ckpt_path) to the keys used by the api_registry (e.g. ckpt). I would just use the same keys for both - this would reduce the chance of mistakes and allow us to add arbitrary files with arbitrary keys whenever necessary