gesture_x_detector

Support onLongPressEnd

BREAKING: opt into null safety feat!: upgrade Dart SDK constraints to >=2.12.0-0 <3.0.0

BREAKING

• add new flag: bypassMoveEventAfterLongPress

    by default it is true, means after receive long press event without release pointer (finger still touch on screen the move event will be ignore.
  
    set it to false in case you expect move event will be fire after long press event
  

• using parameter object instead of naked parameters

    old version
    ```dart
    @override
    Widget build(BuildContext context) {
        return XGestureDetector(
        child: Text("data"),
        onTap: (pointer, localPos, position) => print("localPos: $localPos, pointer: $pointer"),
        onScaleUpdate: (changedFocusPoint, scale, rotationAngle) =>
            print("focalPoint: $changedFocusPoint, scale: $scale"),
        );
    }
    ```
  
    new version
    ```
    Widget build(BuildContext context) {
        return XGestureDetector(
        child: Text("data"),
        onTap: (event) =>
            print("localPos: ${event.localPos}, pointer: ${event.pointer}"),
        onScaleUpdate: (event) =>
            print("focalPoint: ${event.focalPoint}, scale: ${event.scale}"),
        );
    }
    ```