XRProjectionLayerInit in the webxr layers samples is not the same as in Spec

XRProjectionLayerInit passed to [createProjectionLayer](https://github.com/immersive-web/webxr-samples/blob/main/layers-samples/proj-layer.html#L147) is not the same as defined in [spec](https://immersive-web.github.io/layers/#dictdef-xrprojectionlayerinit). Other layer samples also seem to be in-consistent in the same way.