[graphite] Implement VulkanCommandBuffer::onCopyBufferToBuffer

* One step towards getting dm running for vulkan.
* Store buffer usage flags as member of VulkanBuffer
* Add src/dst buffer usage flag assertions onto existing copy calls that involve buffers

Change-Id: I163efe06600536216531b349ece7936b9ee6d913
Bug: b/270608947
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/648597
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Nicolette Prevost <nicolettep@google.com>
3 files changed