fix: support cameras array

[xiaoiver]

🤔 This is a ...

• New feature
• Bug fix
• Site / Document optimization
• TypeScript definition update
• Refactoring
• Performance improvement
• Code style optimization
• Test Case
• Branch merge
• Other (about what?)

🔗 Related issue link

In WebXR there're multiple XRViews e.g. left and right eyes. So we need to support rendering to cameras instead of a single camera.

https://threejs.org/docs/#api/en/cameras/ArrayCamera

💡 Background and solution

Since we use RenderGraph now, each camera should have its own render pass.

this.cameras.forEach(({ viewport }) => {
    // main render pass
    this.builder.pushPass((pass) => {});
});

📝 Changelog

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☑️ Self Check before Merge

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

[xiaoiver]

目前确实能根据左右眼相机渲染两次：

但右眼相机渲染完才设置 viewport，导致重合在一起：

[xiaoiver]

第二个问题是 z-fighting 导致的闪烁：

https://threejs.org/examples/webgl_camera_logarithmicdepthbuffer.html