Add HfFileSystem.url method

[mariosasko]

Adds a url method to the HfFileSystem to simplify converting HF paths to HTTP URLs, which should be useful when working with libs that support HTTP URLs but not fsspec paths as input/output (e.g., webdataset, polars, etc.).

PS: The url method is not part of the official fsspec specification, but popular filesystem implementations such as gcsfs and s3fs also have it

[HuggingFaceDocBuilderDev]

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[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (0c272d5) 82.37% compared to head (ab935a4) 82.37%.
Report is 2 commits behind head on main.

❗ Current head ab935a4 differs from pull request most recent head be04be6. Consider uploading reports for the commit be04be6 to get more accurate results

Files	Patch %	Lines
src/huggingface_hub/hf_file_system.py	77.77%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2027      +/-   ##
==========================================
- Coverage   82.37%   82.37%   -0.01%     
==========================================
  Files          66       66              
  Lines        8240     8249       +9     
==========================================
+ Hits         6788     6795       +7     
- Misses       1452     1454       +2     

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[Wauplin]

Thanks for the addition! Left a few nits but looks good to me :) Feel free to merge.

[lhoestq]

Nice thanks !

[Wauplin]

Thanks for applying the changes!