Clean up hub
# What does this PR do?

This PR removes all uses of the old utils in Transformers to migrate to the new version using `cached_file`, and remove said utils from the Transformers library.
It is slightly breaking since we remove objects (in particular `cached_path` is in the main init albeit not documented), but those are all internal tools, so it's okay in my opinion. Only the research examples are left as before.
_The documentation is not available anymore as the PR was closed or merged._<|||||>I still had an error mentioning `ImportError: cannot import name 'cached_path' from 'transformers.utils' `
@ `tf.__version__ == '2.11.0'`. Is this related? What should i do?<|||||>You should stop using that function, as it has been removed from `transformers.utils` in the most recent versions.