This PR adds a new operator to run a node group on object geometry.
Only curves sculpt mode is supported for now, to simplify the design.
A new geometry node editor context to edit operator groups is also
added. This allows changing any node group, rather than only node
groups that are part of the active modifier context.
3D viewport menus are added with any geometry node group
asset in a catalog that contains the `Operator` tag. Currently Blender
must be restarted to refresh the list of available operators.
This is only the first phase of the node group operator feature.
Many more features will be added in next steps.
See #101778
Pull Request: https://projects.blender.org/blender/blender/pulls/108947
e4cc91a611