Implement native drag from Selector to a given offset

[fylyppo]

Use case

• Dragging native sliders
• Choosing date in iOS system date picker

Proposal

await $.native.dragFrom(Selector selector, Offset offset);

[kodega2016]

you can use widget tester to drag to the offset.

WidgetTester tester = $.tester;
final centerOfTheSignatureView = $(SignatureView).hitTestable();

await tester.timedDrag(
  centerOfTheSignatureView,
  const Offset(100, 100),
  const Duration(milliseconds: 500),
);