This patch improves conversion method from NURBS to Bezier curves,
resulting in exact shape between those two types when provided with
a 3rd degree NURBS curve. Part of T86086.
See the differential revision for more comparisons.
The node still cannot account properly for a NURBS "order" other
than 4 and it does not take into account control point weights.
Differential Revision: https://developer.blender.org/D13546
a84621347d