Add endpoint param to hf_hub_url

[mariosasko]

As discussed in huggingface/hffs#1, it would be nice to add the endpoint param to hf_hub_url to support passing custom endpoints (useful for private Hub users)

[osanseviero]

One can set the HF_ENDPOINT environment variable to change the endpoint, which was added with private Hub use cases in mind

https://github.com/huggingface/huggingface_hub/blob/main/src/huggingface_hub/constants.py#L42

[Wauplin]

Thanks @mariosasko for opening the ticket and thanks @osanseviero for providing a solution :)
Environment variable is a good way to solve that but let's keep this issue open. Wouldn't hurt to have 2 ways of settings the endpoint.

For the record, request is related to hffs implementation: huggingface/hffs#1 (comment)

[julien-c]

in hffs context, what's the use case for setting an endpoint?

[mariosasko]

@julien-c For easier testing (see huggingface/hffs#1 (comment))

I can remove the endpoint param for now and use the env variable instead, but then we need to use patching, which makes the tests more complex (I assume HfApi has this param for the same reason).

[severo]

fyi, we have code in datasets-server that depend on this

https://github.com/huggingface/datasets-server/pull/1296/files#diff-706957870370898392d2283826314dc06e70e585c298f3d63154669dfc23cbc3R417

[Wauplin]

Done in #1580.