Define API for View Transition

Define an API to support the CSS pseudo-elements and `@`-rules that are part of the [View Transition API](https://developer.mozilla.org/en-US/docs/Web/API/View_Transition_API).

```css
::view-transition-group()
::view-transition-image-pair()
::view-transition-old()
::view-transition-new()
```

For example:

```tsx
const viewTransition = stylex.viewTransition({
group?: {},
imagePair?: {},
old?: {},
new?: {},
});
```