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.

Beginnen Sie mit den Implementierungen von fig.add_vline(), fig.add_hline(), fig.add_hrect() und fig.add_vrect(), und vergleichen Sie anschließend deren Umgang mit Annotationen mit der Unterstützung von Plotly.js für shape.label. Überprüfen Sie, dass die vier Hilfsfunktionen shape labels anstelle separater annotation objects verwenden und dabei ihre label arguments und ihr placement behavior beibehalten.