WebGPU: Stream client arrays Add support for vertex attributes and index data without buffer backings. Stream the data to buffers at draw time. Bug: angleproject:368602384 Change-Id: I697b7882cdebf0dfab08fcffabd2d36048920547 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5878137 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>