IVGCVSW-3418 Add Arm NN front end support for the new Stack layer

 * Added new StackLayer class
 * Made necessary changes to Descriptors, ILayerSupport, ILayerVisitor, etc.
 * Added unit tests

Signed-off-by: Matthew Jackson <matthew.jackson@arm.com>
Change-Id: Ieb97a928a342ffe1901c6058eb895711c358fd3d
diff --git a/src/armnn/Network.cpp b/src/armnn/Network.cpp
index 3b7a1cf..2949381 100644
--- a/src/armnn/Network.cpp
+++ b/src/armnn/Network.cpp
@@ -1422,6 +1422,12 @@
     return layer;
 }
 
+IConnectableLayer* Network::AddStackLayer(const StackDescriptor& stackDescriptor,
+                                          const char* name)
+{
+    return m_Graph->AddLayer<StackLayer>(stackDescriptor, name);
+}
+
 void Network::Accept(ILayerVisitor& visitor) const
 {
     for (auto layer : GetGraph())