Add offline mode for agents
# What does this PR do?

This PR adds a check in the remote tools setup to bypass it when Transformers is in offline mode.
Fixes #25223
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_25226). All of your documentation changes will be reflected on that endpoint.<|||||>I'm getting an error:

```
ValueError: image-transformation is not implemented on the Hub.
```

It's coming from ```_setup_default_tools``` called from the ```__init__```.

It's because of the for loop that check ```HUGGINGFACE_DEFAULT_TOOLS_FROM_HUB```.<|||||>Thanks for the check! Could you try again with the updated branch?<|||||>It's working great!
Thank you!