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: [
]
}
}
```
Navigator.push allows us to open a new screen. Currently it starts a new Activity with the screen
as it’s root view, but this is only a temporary behaviour. The intended behaviour is similar to
View Controllers on iOS which allows you to manage view hierarchies or a stack of fragments
managed by FragmentManager on Android.