Add connection-related VisualShader operations

- Insert a node in a connection
- Drop an unconnected node on a connection to insert it
- Delete a connection

scene/resources/visual_shader.cpp

@@ -246,6 +246,20 @@ void VisualShaderNode::set_input_port_connected(int p_port, bool p_connected) {
 	connected_input_ports[p_port] = p_connected;
 }
 
+bool VisualShaderNode::is_any_port_connected() const {
+	for (const KeyValue<int, bool> &E : connected_input_ports) {
+		if (E.value) {
+			return true;
+		}
+	}
+	for (const KeyValue<int, int> &E : connected_output_ports) {
+		if (E.value > 0) {
+			return true;
+		}
+	}
+	return false;
+}
+
 bool VisualShaderNode::is_generate_input_var(int p_port) const {
 	return true;
 }