createMapSignal<K, V>  method 
Create a MapSignal
Implementation
MapSignal<K, V> createMapSignal<K, V>(
  Map<K, V> value, {
  String? debugLabel,
  bool autoDispose = true,
}) {
  final s = MapSignal<K, V>(
    value,
    debugLabel: debugLabel,
    autoDispose: autoDispose,
  );
  _watch(s, true);
  return s;
}