feat: Support API token for scanning hf://

[nameexhaustion]

Adds support for scanning from private repositories with an API token:

pl.scan_csv(
    "hf://...",
    storage_options={"token": "..."},
)

or alternatively, using an environment variable

export HF_TOKEN=...
python main.py

ref #17625

[codecov]

Codecov Report

Attention: Patch coverage is 10.00000% with 81 lines in your changes missing coverage. Please review.

Project coverage is 80.40%. Comparing base (235cad3) to head (e6d61dd).
Report is 2 commits behind head on main.

Files	Patch %	Lines
crates/polars-io/src/cloud/options.rs	9.37%	58 Missing ⚠️
crates/polars-io/src/path_utils/hugging_face.rs	0.00%	19 Missing ⚠️
crates/polars-io/src/cloud/object_store_setup.rs	0.00%	3 Missing ⚠️
crates/polars-io/src/path_utils/mod.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17682      +/-   ##
==========================================
+ Coverage   80.37%   80.40%   +0.02%     
==========================================
  Files        1500     1500              
  Lines      196605   196640      +35     
  Branches     2793     2793              
==========================================
+ Hits       158016   158103      +87     
+ Misses      38076    38024      -52     
  Partials      513      513              

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[albertvillanova]

Thanks for the fast implementation.

Just a nit comment: do you think the parameter could be named just "token"? It seems a bit redundant to call it "hf_token" when it is already passed to the "hf://" URL...

[ritchie46]

Can we add an entry in the docstring for discoverability? (Aside from the user guide)

[nameexhaustion]

update docs for source to point to cloud options