Geometry Nodes: initial Attribute Transfer node

This is a first version of an Attribute Transfer node. It only supports two
modes for mapping attributes from one geometry to another for now.
More options are planned for the future.

Ref T87421.

Differential Revision: https://developer.blender.org/D11037

release/scripts/startup/nodeitems_builtins.py

@@ -498,6 +498,7 @@ geometry_node_categories = [
         NodeItem("GeometryNodeAttributeSeparateXYZ"),
         NodeItem("GeometryNodeAttributeRemove"),
         NodeItem("GeometryNodeAttributeMapRange"),
+        NodeItem("GeometryNodeAttributeTransfer"),
     ]),
     GeometryNodeCategory("GEO_COLOR", "Color", items=[
         NodeItem("ShaderNodeValToRGB"),