Add ability to upload folder with upload_file

Is your feature request related to a problem? Please describe. In the spirit of moving away from forcing users to deal with git, it would be nice to allow folks to upload entire folders using upload_file, instead of having them glob/walk through all the files and call upload_file each time.

Describe the solution you’d like

from huggingface_hub import upload_file

# Uploads contents of `images/` to `nateraw/some-repo`
upload_file('nateraw/some-repo', './images/')

Describe alternatives you’ve considered

Bonus points if we have “compression” options as well (zip, tar, gz, etc). If we do that though, we should be mindful of potentially including decompression options in the proposed download_file function #460

Additional context Wanted to upload a few small folders and found myself having to write more code than I wanted to in order to loop over all my local files and call upload_file.

[osanseviero]

IMO instead of supporting uploading folders with upload_file, I would rather have a separate method upload_folder or upload_files which allows receiving a directory (or file pattern even!) to upload multiple files.

WDYT @LysandreJik?

[nateraw]

Closed with #888