feat: add data binding artboards support

[mfazekas]

Summary

• Add support for swapping artboards at runtime via data binding properties
• Enables composing complex scenes from artboards in different Rive files

New APIs

• RiveFile.getBindableArtboard(name) - create bindable artboard reference
• RiveFile.artboardNames / artboardCount - enumerate artboards
• ViewModelInstance.artboardProperty(path) - get artboard property
• ViewModelArtboardProperty.set(artboard) - swap artboard at runtime

Example

const mainFile = useRiveFile(require('./scene.riv'));
const assetsFile = useRiveFile(require('./characters.riv'));

const instance = mainFile.defaultArtboardViewModel()?.createDefaultInstance();
const artboardProp = instance.artboardProperty('CharacterArtboard');

// Swap to a different character
const character = assetsFile.getBindableArtboard('Character 1');
artboardProp.set(character);

rive.mov

References

• Rive Data Binding Docs
• rive-react example