Instead of having the Rigify meta-rigs directly in the 'Add → Armature`
menu, move them into 'Add → Armature → Rigify Meta-Rigs`.
This also removes the " (Meta-Rig)" suffix from every individual
meta-rig menu item.
This serves multiple purposes:
- It's now clear that these meta-rigs come from Rigify.
- The built-in 'Single Bone' armature now has similar visual weight as
the 'Rigify Meta-Rigs' menu item.
- Opens up the menu in a fairer way to other add-ons, to add their own
entries in a similar way.
Pull Request: https://projects.blender.org/blender/blender/pulls/123833
246b317bd4