feat: add data binding lists support

[mfazekas]

Summary

Adds ViewModelListProperty for dynamic list management at runtime, aligned with rive-react API.

API

• length - get list size
• getInstanceAt(index) - get ViewModelInstance at index
• addInstance(instance) - add to end of list
• addInstanceAt(instance, index) - insert at position
• removeInstance(instance) - remove by reference
• removeInstanceAt(index) - remove at index
• swap(index1, index2) - swap items
• addListener(callback) - observe changes

Example

const listProperty = instance.listProperty('items');

// Add new item
const newItem = viewModel.createInstance();
listProperty.addInstance(newItem);

// Remove item
listProperty.removeInstanceAt(0);

// Swap items
listProperty.swap(0, 1);

Test plan

• Added example page with list.riv test file
• iOS implementation
• Android implementation

Closes #11

[HayesGordon]

LGTM! Just need to decide if these methods names will be most familiar for RN

[HayesGordon]

Oh and all of the abstraction and Nitro is really paying off here 🙌 . This is really minimal code for a large feature.

[HayesGordon]

LGTM!