Add Lottie Export

[JimSEOW]

We now finally have Xamarin Lottie support for iOS, Android and UWP.

First use case: Animated gradient, export to SkiaSharp, use SkiaSharp (UWP) to control the manner and speed of transition and use the C# LottieUWP library to export Lottie File for use in OneGUI4All (XAML Standard) Ecosystem.

Second use case: Eventually add Keyframe control (e.g. similar to Blend for Visual Studio) to KimonoDesigner and export Lottie file.