Fix: notebook_login() does not update UI on Databricks

[fwetdb]

Fixes 1384

The PR adjusts notebook_login() to use the ipywidgets Box output to print the feedback.
This enables the logic to work in all notebooks that are compatible with ipywidgets - including Databricks where clear_output does not work.

Examples for the code flow:

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[Wauplin]

Hey @fwetdb thanks for working on this! At first glance PR looks good :)

I'll make some tests in different environments (colab/jupyter, python3.7/3.10) soon and get back to you for a proper review. If you see some code quality issues, don't worry I can handle them.

[Wauplin]

Hi @fwetdb, I made some tests and it works great! I think we are good to go. I pushed some code to your branch. Instead of the add_string_to_widget_output method passed as argument, I re-used a utility that we have in our tests that redirects the output from print to a buffer. I prefer it this way so that we don't change _login itself. I hope you are fine with me changing it 🙏

@osanseviero could you have a second look please as it impact all our notebook users? I made a colab for you to quickly test the new UI. The main change is that the returned message ("you're logged in !") is not printed from the terminal but displayed as a widget (and centered). For context, the goal is to avoid clear_output() that is not handled by Databricks. cc @LysandreJik that might have an opinion as well.

(For testing, I tried jupyter notebook on Python 3.7 and 3.10 + tried google Colab. Is there another notebook we should try?)

[osanseviero]

It looks ok from my side! Thanks for the fix

[julien-c]

LGTM too and quite happy that we improve our support of Databricks / Databricks notebooks 👍

[fwetdb]

Thank you @Wauplin and everyone else involved!
The adjustments look good to me and I just double-checked them on Databricks.
So, good to merge from my side.

[Wauplin]

Good, thanks @fwetdb for double-checking this!
I'm merging the PR then 🎉