Sort animation nodes in AnimationNodeBlendSpace2DEditor popup menu

Updated AnimationNodeBlendSpace2DEditor::_blend_space_gui_input to sort animation nodes for menu when adding new points, to match ordering in AnimationNodeBlendSpace1DEditor and AnimationNodeStateMachineEditor.  Old code had the sort call before adding the node names, so it wasn't reflected in the menu.

Author: aaronp64

editor/plugins/animation_blend_space_2d_editor.cpp

@@ -119,10 +119,11 @@ void AnimationNodeBlendSpace2DEditor::_blend_space_gui_input(const Ref<InputEven
 			menu->clear(false);
 			animations_menu->clear();
 			animations_to_add.clear();
+
 			LocalVector<StringName> classes;
+			ClassDB::get_inheriters_from_class("AnimationRootNode", classes);
 			classes.sort_custom<StringName::AlphCompare>();
 
-			ClassDB::get_inheriters_from_class("AnimationRootNode", classes);
 			menu->add_submenu_node_item(TTR("Add Animation"), animations_menu);
 
 			List<StringName> names;