Change the tab renderer to allow adding closable tab

[brichet]

This PR add a close icon on new closable tab in tree-extension.

Fix #6476

[github-actions]

👈 Launch a Binder on branch brichet/notebook/fix/closable_tab

[jtpio]

Thanks @brichet this can also be useful for #6316.

[jtpio]

Were these prettier changes added automatically on commit?

[jtpio]

Normally the local dev install should pull the right version of prettier.

[brichet]

Yes, I couldn't commit because of prettier check, so I ran jlpm prettier and add the changes.
But the command did have change a lot of files, with the same kind of modification.

[jtpio]

Would you be able to do a clean local install in a new environment to make sure the right dependencies are pulled?

[brichet]

Thanks @jtpio, I had some weird files in node-modules/.bin.
jlpm clean did the trick.

[jtpio]

Nice 👍

[jtpio]

Thanks!