Vulkan: Vertex attribute hole crash workaround * Added condition to bypass reading from a streaming attribute if the source pointer is null. * Added unit test that crash if a vertex pointer is not defined for an enabled vertex attribute. * VertexAttribPointerCopyBufferFromInvalidAddress * Credit for the original test: tingwei.guo Bug: angleproject:359729255 Change-Id: I2592fed66f0eba8c7003ec02cc8ca802833f23b3 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5899978 Commit-Queue: Amirali Abdolrashidi <abdolrashidi@google.com> Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>