Implement Element transition on Android

This commit adds basic support for Element transition to Android.
Currently, only Shared Transition is supported and only when pushing screens.

There are a few caveats you need to be aware of if you intend to use
this feature in its current state:

1. Since elements need to be laid out before the transition can start, Set `waitForRender: true` when pushing the destination screen.
2. Fade animation has to be used when pushing screens with shared elements.

API

```js
options: {
  animations: {
    push: {
      waitForRender: true,
      content: {
        alpha: {
          from: 0,
          to: 1,
          duration: 250
        }
      }
    }
  },
  customTransition: {
    animations: [
    ]
  }
}
```