9db4c0ca4b
Refactor the Add menu in Shading nodes, with manually created menus, inspired by Geometry Nodes and more recently the Compositor. Minor sorting adjustments by splitting categories in groups, with separators in between groups, and sorted alphabetically. Shading node group assets are also populated in the menus. This is the first part of the re-organization of the Add menu, part of #111746 Pull Request: https://projects.blender.org/blender/blender/pulls/111798