Geometry Nodes: new Field at Index node

This node allows accessing data of other elements in the context geometry.
It is similar to the Transfer Attribute node in Index mode. The main difference
is that this node does not require a geometry input, because the context
is used.

The node can e.g. be used to generalize what the Edge Vertices node is doing.
Instead of only being able to get the position of the vertices of an edge,
any field/attribute can be accessed on the vertices.

Differential Revision: https://developer.blender.org/D13825

release/scripts/startup/nodeitems_builtins.py

@@ -757,6 +757,7 @@ geometry_node_categories = [
     ]),
     GeometryNodeCategory("GEO_UTILITIES", "Utilities", items=[
         NodeItem("GeometryNodeAccumulateField"),
+        NodeItem("GeometryNodeFieldAtIndex"),
         NodeItem("ShaderNodeMapRange"),
         NodeItem("ShaderNodeFloatCurve"),
         NodeItem("ShaderNodeClamp"),