Geometry Nodes: new Realize Instances node

This node has a simple geometry input and output.
If the input geometry contains instances, they will be realized
into actual geometry. When there are many instances, this can
be very slow and memory intensive. Generally, instances should
only be made real when necessary, e.g. when every instance
should be deformed independently.

Differential Revision: https://developer.blender.org/D12556

release/scripts/startup/nodeitems_builtins.py

@@ -546,6 +546,7 @@ geometry_node_categories = [
         NodeItem("GeometryNodeJoinGeometry"),
         NodeItem("GeometryNodeSeparateComponents"),
         NodeItem("GeometryNodeSetPosition", poll=geometry_nodes_fields_poll),
+        NodeItem("GeometryNodeRealizeInstances", poll=geometry_nodes_fields_poll),
     ]),
     GeometryNodeCategory("GEO_INPUT", "Input", items=[
         NodeItem("GeometryNodeObjectInfo"),