Signals: Manually port most of remaining connect_compat uses

It's tedious work...

Some can't be ported as they depend on private or protected methods
of different classes, which is not supported by callable_mp (even if
it's a class inherited by the current one).

editor/scene_tree_editor.cpp

@@ -1089,6 +1089,7 @@ void SceneTreeEditor::set_connecting_signal(bool p_enable) {
 
 void SceneTreeEditor::_bind_methods() {
 
+	ClassDB::bind_method("_update_tree", &SceneTreeEditor::_update_tree); // Still used by some connect_compat.
 	ClassDB::bind_method("_rename_node", &SceneTreeEditor::_rename_node);
 	ClassDB::bind_method("_test_update_tree", &SceneTreeEditor::_test_update_tree);