This commit adds an option to interpolate the number of control points
in new curves based on the count in neighboring existing curves. The
idea is to provide a more automatic default than manually controlling
the number of points in a curve, so users don't have to think about
the resolution quite as much.
Internally, some utilities for creating new curves are extracted to a
new header file. These can be used for the various nodes and operators
that create new curves.
The top-bar UI will be adjusted in a separate patch, probably moving
all of the settings that affect the size and shape of the new curves
into a popover.
Differential Revision: https://developer.blender.org/D14877
