Vulkan: Simple buffer creation. This is necessary to initialize vertex arrays. BUG=angleproject:1579 Change-Id: Ic5a232d5cdfaa75b41241901de842e62ff3b173f Reviewed-on: https://chromium-review.googlesource.com/406645 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org>