Improve the user experience for resetting Jupyterlite.

[MarcSkovMadsen]

I just discovered by coincidence that the Getting_Started notebook in Panelite now contains functionality to reset. This is great.

I think the functionality can improved

• Make it more easily discoverable by putting in separate, clearly named notebook.
• Avoid having to import, run and scroll down. This is slow. This can be avoided by putting it in separate notebook. (Yes. I know you don't have to import and run. But its just a very natural thing to do).
• Send a clear signal that the storage has been cleared. Today when you click the button nothing visible happens. Thus you don't feel confident that the script finished with success.

Furthermore as a developer

• I cannot find the Getting_Start.ipynb notebook via my IDE because its actually ignored in the gitignore. So its simply excluded by VS code.
• I do not get the notebook cleaned when I use pre-commit because its actually skipped in the configuration.

This PR fixes these issues.

[philippjfr]

Good idea, thanks!