IVGCVSW-3739 Add Arm NN front end support for Abs Layer

	* Add Abs Layer
	* Add no-op factory implementations for CpuRef, CpuAcc, GpuAcc
	* Add Queue Descriptor in WorkloadData
	* Add IsAbsLayerSupported to LayerSupport
	* Add LayerVisitor tests

Signed-off-by: Kevin May <kevin.may@arm.com>
Change-Id: Ib0992571d1c80de851cea466291be904e9bdb430
diff --git a/src/armnnSerializer/Serializer.cpp b/src/armnnSerializer/Serializer.cpp
index faf3d82..56d313f 100644
--- a/src/armnnSerializer/Serializer.cpp
+++ b/src/armnnSerializer/Serializer.cpp
@@ -105,6 +105,11 @@
     CreateAnyLayer(flatBufferOutputLayer.o, serializer::Layer::Layer_OutputLayer);
 }
 
+void SerializerVisitor::VisitAbsLayer(const armnn::IConnectableLayer* layer, const char* name)
+{
+    throw UnimplementedException("SerializerVisitor::VisitAbsLayer is not implemented");
+}
+
 // Build FlatBuffer for Activation Layer
 void SerializerVisitor::VisitActivationLayer(const armnn::IConnectableLayer* layer,
                                              const armnn::ActivationDescriptor& descriptor,