fix: link to HF repo/tree/revision when a file is missing

[mapmeld]

When cached_file fails to download a file from a valid HF model, it reports Checkout 'https://huggingface.co/{path_or_repo_id}/{revision}' for available files. But this gets a 404. The correct link would include /tree/{revision}.

• It works for both branch names (e.g. main) and commit IDs
• Another error message already uses this URL https://github.com/huggingface/transformers/blob/main/src/transformers/utils/hub.py#L371
  ( edit: update path to hub files in the error message #29369 )

I had the error come up when trying to load a tokenizer from a LoRA repo instead of the base model repo: https://colab.research.google.com/drive/1pqdFMgo_6kqHfCGR5-qCIC6A_py5f84H?usp=sharing

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[amyeroberts]

Thanks for fixing!