This commit contains various new features for curves sculpt mode
that have been developed in parallel.
* Selection:
* Operator to select points/curves randomly.
* Operator to select endpoints of curves.
* Operator to grow/shrink an existing selection.
* New Brushes:
* Pinch: Moves points towards the brush center.
* Smooth: Makes individual curves straight without changing the root
or tip position.
* Puff: Makes curves stand up, aligning them with the surface normal.
* Density: Add or remove curves to achieve a certain density defined
by a minimum distance value.
* Slide: Move root points on the surface.
Differential Revision: https://developer.blender.org/D15134
416aef4e13