Add support for multiview with WebGPURenderer

You can use the new WebGPURenderer with aframe 1.7.1 with importmap, if you alias three to three.webgpu.js, aframe will use WebGPURenderer instead of WebGLRenderer, see source of the example https://aframe.io/aframe/examples/showcase/webgpu/ and using the latest super-three 0.177.0. But to use multiview with WebGPURenderer you will need a change here https://github.com/aframevr/aframe/blob/9ff61ffaf98c42b255fb17674eddb0d85c3239ba/src/core/scene/a-scene.js#L529-L547 the option is just called multiview and not multiviewStereo in WebGPURenderer it seems https://github.com/mrdoob/three.js/blob/b8f5c787fe6afbcbc442a6990f36a6c42d7405ca/src/renderers/webgpu/WebGPURenderer.js#L40C26-L40C35

Update the example https://aframe.io/aframe/examples/performance/multiview-extension/?multiview=on or duplicate it to test it with the new WebGPURenderer. I was answering this on discord, so I'm creating the issue if anyone want to test it and do the PR.