Support private datasets
For now, only public datasets can be queried.

To support private datasets :
- [x] add `use_auth_token` argument to all the queries functions (and upstream too in https://github.com/huggingface/datasets/blob/master/src/datasets/inspect.py)
- [x] obtain the authentication header <strike>or cookie</strike> from the request
Support private datasets: For now, only public datasets can be queried.

To support private datasets :
- [x] add `use_auth_token` argument to all the queries functions (and upstream too in https://github.com/huggingface/datasets/blob/master/src/datasets/inspect.py)
- [x] obtain the authentication header <strike>or cookie</strike> from the request