Start of Bevel V2, as being worked on with task T98674.

This is the start of a geometry node to do edge, vertex, and face
bevels.

It doesn't yet do anything but analyze the "Vertex cap" around
selected vertices for vertex bevel.

release/scripts/startup/nodeitems_builtins.py

@@ -107,6 +107,7 @@ def mesh_node_items(context):
     space = context.space_data
     if not space:
         return
+    yield NodeItem("GeometryNodeBevelMesh")
     yield NodeItem("GeometryNodeDualMesh")
     yield NodeItem("GeometryNodeExtrudeMesh")
     yield NodeItem("GeometryNodeFlipFaces")