Vulkan: Use BindIndexBuffer2 when available This Vulkan API becomes available with VK_KHR_maintenance5. In addition to the original args, it also takes the index buffer size. * Added the necessary functions to use the following API: vkCmdBindIndexBuffer2KHR() * handleDirtyGraphicsIndexBuffer() now uses this API if maintenance5 is available. Bug: angleproject:394337110 Change-Id: I9a650ac5a033b449da05e0c226e2cfb6df74a75c Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6735725 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Amirali Abdolrashidi <abdolrashidi@google.com> Reviewed-by: Charlie Lao <cclao@google.com>