IVGCVSW-2555 Add no-op implementation for Detection PostProcess

 * Added DetectionPostProcessQueueDescriptor to WorkloadData
 * Added CreateDetectionPostProcess function in WorkloadFactory.hpp
 * Added stub implementation of the CreateDetectionPostProcess
in workload factories
 * Added DetectionPostProcessLayer stub implementation
 * Added AddDetectionPostProcessLayer to Network
 * Added IsDetectionPostProcessSupported to LayerSupportBase

Change-Id: Ifc071b3b6b12877c997bdcc43d769c8f891d5c6c
diff --git a/src/backends/reference/RefWorkloadFactory.cpp b/src/backends/reference/RefWorkloadFactory.cpp
index 75a9efd..103abdd 100644
--- a/src/backends/reference/RefWorkloadFactory.cpp
+++ b/src/backends/reference/RefWorkloadFactory.cpp
@@ -151,6 +151,12 @@
         RefDepthwiseConvolution2dUint8Workload>(descriptor, info);
 }
 
+std::unique_ptr<IWorkload> RefWorkloadFactory::CreateDetectionPostProcess(
+    const armnn::DetectionPostProcessQueueDescriptor& descriptor, const armnn::WorkloadInfo& info) const
+{
+    return MakeWorkload<NullWorkload, NullWorkload>(descriptor, info);
+}
+
 std::unique_ptr<armnn::IWorkload> RefWorkloadFactory::CreateNormalization(
     const NormalizationQueueDescriptor& descriptor, const WorkloadInfo& info) const
 {