- Move patch point tracking from pipeline state to render state, and
remove MVKPipelineCommandEncoderState subclasses no longer needed.
- Move sample location tracking from renderpass input to pipeline
static or dynamic state tracking.
- Restart Metal render pass when sample locations change, and enable
VkPhysicalDeviceSampleLocationsPropertiesEXT::variableSampleLocations.
- Fix regression that broke VK_POLYGON_MODE_LINE (unrelated).
- Fix regression in marking MVKRenderingCommandEncoderState
dirty after vkCmdClearAttachments() (unrelated).