Vulkan: Add dynamic vertex buffers to graph With DynamicBuffer outputting BufferHelper objects, these objects can participate in the command graph, i.e. record commands. This means they need appropriate dependencies in the graph as well as pipeline barriers. There are a few users of DynamicBuffer for which this change should be applied to. This change covers vertex attribute buffers. Bug: angleproject:2958 Change-Id: Ic3f8e187639919aba23102bba238de9ce70e6394 Reviewed-on: https://chromium-review.googlesource.com/c/1364450 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>