Enhance the rounded rectangle implementation (#5597)

Enhance the rounded rectangle implementation (#5597)

Use `arcTo` instead of `quadraticCurveTo` (both methods have the same compatibility level) because it generates better results when the final rect is a circle but also when it's actually a rectangle and not a square. This change is needed by the datalabels plugin where the user can configure the `borderRadius` and thus generate circle from a rounded rectangle.