Dynamic Properties

## 🚀 Feature Requests

Lottie offers a Dynamic Properties feature that lets you modify properties in animations at runtime so you can e.g. recolor parts or change positions of elements.
Details for iOS here : https://airbnb.io/lottie/ios/dynamic.html
and Android here : https://airbnb.io/lottie/android/dynamic.html

Can we have this for Xamarin ?

### Describe the feature
From the Lottie Website :

> Lottie can do more than just play beautiful animations. Lottie allows you to change animations at runtime. Changing animations is done through Lottie's dynamic properties API. The dynamic properties API features a class for searching through animation data, LOTKeypath, a protocol for setting animation data LOTValueDelegate, several helper objects for common animation scenarios LOTValueCallback, LOTBlockCallback, LOTInterpolatorCallback, and finally a method for setting animation delegates on LOTAnimationView setValueDelegate:forKeypath:.

### Platforms affected (mark all that apply)
- [ x] :iphone: iOS
- [x ] :robot: Android
- [x ] :checkered_flag: WPF
- [x ] :earth_americas: UWP
- [x ] :apple: MacOS
- [x ] :tv: tvOS
- [x ] :monkey: Xamarin.Forms

The issue names no files, tests, or entry points. Start by reading the linked iOS and Android dynamic-properties documentation, then determine the Xamarin platforms and API scope to support; done means dynamic animation properties can be modified at runtime across the requested platforms.

Written by the indexing model from the issue text.