Vulkan: Add DispatchUtilsVK This class provides a set of compute-based internal utilities. Currently, buffer clear and copy are implemented. Other possibilities include more efficient mip map generation, or specialized texture operations. VertexArrayVk::updateIndexTranslation() is updated to convert the GL_UNSIGNED_BYTE index buffer to a GL_UNSIGNED_SHORT one using this class to avoid a CPU readback. The vk::Format class is augmented with a few flags (IsInt, IsUnsigned) to be able to select the appropriate shader based on the format (float, int or uint). Bug: angleproject:2958,angleproject:3003 Change-Id: Ie35519deb3c32a3da5ccf74080c70092c9287f0a Reviewed-on: https://chromium-review.googlesource.com/c/1336307 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>