Geometry Nodes: Move mesh primitives to their own category

It makes more sense to avoid mixing the primitives with other mesh
operations. We considered adding a "Mesh" prefix to the names too,
but decided to prioritize improvements to the node search menu instead,
and only consider that if there is an overlapping prefix name for
another data type.

release/scripts/startup/nodeitems_builtins.py

@@ -521,15 +521,6 @@ geometry_node_categories = [
         NodeItem("GeometryNodeSubdivisionSurface"),
         NodeItem("GeometryNodeSubdivide"),
 
-        # These should be in a sub-menu, but that requires a refactor to build the add menu manually.
-        NodeItem("GeometryNodeMeshCube"),
-        NodeItem("GeometryNodeMeshCircle"),
-        NodeItem("GeometryNodeMeshUVSphere"),
-        NodeItem("GeometryNodeMeshIcoSphere"),
-        NodeItem("GeometryNodeMeshCylinder"),
-        NodeItem("GeometryNodeMeshCone"),
-        NodeItem("GeometryNodeMeshLine"),
-        NodeItem("GeometryNodeMeshPlane"),
     ]),
     GeometryNodeCategory("GEO_POINT", "Point", items=[
         NodeItem("GeometryNodePointDistribute"),
@@ -544,6 +535,16 @@ geometry_node_categories = [
         NodeItem("GeometryNodePointsToVolume"),
         NodeItem("GeometryNodeVolumeToMesh"),
     ]),
+    GeometryNodeCategory("GEO_PRIMITIVES", "Mesh Primitives", items=[
+        NodeItem("GeometryNodeMeshCube"),
+        NodeItem("GeometryNodeMeshCircle"),
+        NodeItem("GeometryNodeMeshUVSphere"),
+        NodeItem("GeometryNodeMeshIcoSphere"),
+        NodeItem("GeometryNodeMeshCylinder"),
+        NodeItem("GeometryNodeMeshCone"),
+        NodeItem("GeometryNodeMeshLine"),
+        NodeItem("GeometryNodeMeshPlane"),
+    ]),
     GeometryNodeCategory("GEO_UTILITIES", "Utilities", items=[
         NodeItem("ShaderNodeMapRange"),
         NodeItem("ShaderNodeClamp"),