Refactor `add_vline()`, `add_hline()`, `add_hrect()`, `add_vrect()` to use Plotly.js `shape.label` attribute

The Plotly.py functions fig.add_vline(), fig.add_hline(), fig.add_hrect(), fig.add_vrect() accept arguments such as annotation_text which are used to create a label for the shape. This is done by creating and adding two separate objects to the Plotly.js layout: a shape, and an annotation.

However, now that Plotly.js has added support for shape labels, this is no longer necessary -- the text can be added directly as a label to the shape rather than creating two separate objects.

This would solve issues such as https://github.com/plotly/plotly.py/issues/3065 where we are doing some hacky stuff to get the label in the right place.

Commencez par les implémentations de fig.add_vline(), fig.add_hline(), fig.add_hrect() et fig.add_vrect(), puis comparez leur gestion des annotations avec la prise en charge de shape.label par Plotly.js. Vérifiez que les quatre helpers utilisent des shape labels plutôt que des annotation objects distincts, tout en préservant leurs label arguments et leur placement behavior.