onProgressNotification method
Register a handler for progress updates from the server: the whole
notifications/progress params (token, progress, total, message).
Implementation
void onProgressNotification(void Function(ProgressNotificationParams progress) handler) {
onNotification(McpProtocol.methodProgress, (params) {
handler(ProgressNotificationParams.fromJson(Map<String, Object?>.from(params)));
});
}