Support loading models from huggingface

[guenthermi]

We would like to implement something like a load_from_hf function in the finetuner client to support loading our models from the hugging face hub.

The models should be stored on the hf hub in the same format as they are stored on hubble / locally. For now we only want to manually upload model which can be used via finetuner. The new load_from_hf function should use the huggingface client library to download all files and our existing get_model functions can then be used to load the model.

[bwanglzu]

#751