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zink: Eliminate no-op command buffers

zink is submitting many no-op VkCommandBuffers when replaying an apitrace of Unturned(1). Strictly speaking, the command buffers do things on the GPU, such as setting dynamic state, but produce no observable output.

I believe they should eliminated, in order to reduce driver overhead.

Here is an example discovered through gfxrecon:

VkSubmitInfo...

"pCommandBuffers": [
  {
    "commands": [
      "vkBeginCommandBuffer",
      "vkCmdSetAttachmentFeedbackLoopEnableEXT",
      "vkCmdSetPatchControlPointsEXT",
      "vkCmdSetColorWriteEnableEXT",
      "vkCmdPipelineBarrier2",
      "vkEndCommandBuffer"
    ]
  },
  {
    "commands": [
      "vkBeginCommandBuffer",
      "vkCmdSetAttachmentFeedbackLoopEnableEXT",
      "vkCmdSetPatchControlPointsEXT",
      "vkCmdSetAttachmentFeedbackLoopEnableEXT",
      "vkCmdSetColorWriteEnableEXT",
      "vkCmdSetDepthWriteEnable",
      "vkEndCommandBuffer"
    ]
  }
],
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