Blender Git Loki

Geometry Nodes: support minimum twist normal mode

The minimum twist mode is important because it allows creating
normals without sudden changes in direction. The disadvantage
of minimum twist normals is that the normals depend on all control
points. So changing one control point can change the normals
everywhere. The computed normals do not match the existing
code exactly, although they do match quite well on non-cyclic and
on some cyclic curves. I also noticed that the existing implementation
has some fairly simple failure cases that I haven't found in the new
implementation so far.

Differential Revision: https://developer.blender.org/D11621