Add a monitor for the orphan nodes

- Allow the user to keep track of the nodes that might leak
- Possible fix for #27103

scene/main/node.cpp

@@ -41,6 +41,8 @@
 
 VARIANT_ENUM_CAST(Node::PauseMode);
 
+int Node::orphan_node_count = 0;
+
 void Node::_notification(int p_notification) {
 
 	switch (p_notification) {
@@ -84,11 +86,14 @@ void Node::_notification(int p_notification) {
 				add_to_group("_vp_unhandled_key_input" + itos(get_viewport()->get_instance_id()));
 
 			get_tree()->node_count++;
+			orphan_node_count--;
 
 		} break;
 		case NOTIFICATION_EXIT_TREE: {
 
 			get_tree()->node_count--;
+			orphan_node_count++;
+
 			if (data.input)
 				remove_from_group("_vp_input" + itos(get_viewport()->get_instance_id()));
 			if (data.unhandled_input)
@@ -2938,6 +2943,8 @@ Node::Node() {
 	data.use_placeholder = false;
 	data.display_folded = false;
 	data.ready_first = true;
+
+	orphan_node_count++;
 }
 
 Node::~Node() {
@@ -2948,6 +2955,8 @@ Node::~Node() {
 
 	ERR_FAIL_COND(data.parent);
 	ERR_FAIL_COND(data.children.size());
+
+	orphan_node_count--;
 }
 
 ////////////////////////////////