This adds a new operator that converts all selected curves objects
into hair particle systems on their respective surface objects. Existing
particle systems with the correct name are updated, otherwise a new
particle system is added.
The purpose of the operator is the make the new curve sculpting tools
useful even before all functionality is ported over from the old hair system.
The operator can be found in the `Object > Convert` menu in object mode,
when a curves object is active.
Differential Revision: https://developer.blender.org/D14441
3656e66ac2