Geometry Nodes: Make displaying "Manage" panel optional

Often displaying the "Manage" panel is not very useful, or at least it
isn't worth taking up the screen real-estate. This commit adds an option
for showing the panel in the modifier, and adds an option to the node
group which is used to initialize the modifier option when creating a
modifier for a node group asset.

Pull Request: https://projects.blender.org/blender/blender/pulls/146775

scripts/startup/bl_ui/space_node.py

@@ -1121,6 +1121,10 @@ class NODE_PT_node_tree_properties(Panel):
         row.operator("node.default_group_width_set", text="", icon='NODE')
 
         if group.bl_idname == "GeometryNodeTree":
+            row = layout.row()
+            row.active = group.is_modifier
+            row.prop(group, "show_modifier_manage_panel")
+
             header, body = layout.panel("group_usage")
             header.label(text="Usage")
             if body: