Add provider for huggingface.co: Very basic `uri_rewrites`

[julien-c]

Hi!

I use https://nbviewer.org/ quite a bit and we are also considering implementing a notebook-rendering service on huggingface.co that could potentially be built on top of nbconvert and/or nbviewer.

As a quick useful feature, I added URL rewrite from huggingface "blob" URLs, i.e. those you get when navigating to a ipynb file inside a repository, to the "resolve" URLs which we use to serve actual content.

This works for both:

• files stored in raw git: e.g. https://huggingface.co/pceiyos/fake_news_detection_nlp/blob/main/Fake_News_Classificaton.ipynb
• files stored in LFS, i.e. large notebooks over 10MB (also related to #664): https://huggingface.co/spaces/NimaBoscarino/climategan/blob/main/notebooks/plot_metrics.ipynb

Let me know if this looks ok!

[SylvainCorlay]

This looks good to me. I approved the CI to run and will merge if it turns out green!

[julien-c]

Thanks for merging! will look for it when it's deployed.

[SylvainCorlay]

Thanks for merging! will look for it when it's deployed.

This is not done upon merging PRs (An explicit action must be taken).

[SylvainCorlay]

@julien-c there you go!