Add option to disable animation

[GaelSauzet]

Adding a bool "Animated" BindableProperty to enable or disable animation.

Having option to show the animation or not would be nice to have.
If implemented, the SKCanvasView have to be invalidated animated or not after IsCheckedChanged event to redraw the canvas.

In rare instances, spamming the Checkbox will throw a InvalidOperationException due to the animation Task index getting mixed up.

[hnabbasi]

That's a valid request. Will get that in in coming release 👍