IVGCVSW-4549 Add front end for new QLSTM layer

* Added new layer QLstm (Android R HAL 1.3)
* Made necessary updates to APIs
* Added unit tests
* This layer is functionally equivalent to the
  original unquantized LSTM layer with some
  additonal quantization features added. Due
  to this, original LstmParams are used for
  this layer.

Signed-off-by: James Conroy <james.conroy@arm.com>
Change-Id: I5b7f2d2fb6e17e81573b41a31bc55f49ae79608f
diff --git a/src/armnnSerializer/Serializer.cpp b/src/armnnSerializer/Serializer.cpp
index 47b5d05..37ab326 100644
--- a/src/armnnSerializer/Serializer.cpp
+++ b/src/armnnSerializer/Serializer.cpp
@@ -1330,6 +1330,16 @@
     CreateAnyLayer(flatBufferLayer.o, serializer::Layer::Layer_TransposeLayer);
 }
 
+void SerializerVisitor::VisitQLstmLayer(const armnn::IConnectableLayer* layer,
+                                        const armnn::QLstmDescriptor& descriptor,
+                                        const armnn::LstmInputParams& params,
+                                        const char* name)
+{
+    IgnoreUnused(layer, descriptor, params, name);
+
+    throw UnimplementedException("SerializerVisitor::VisitQLstmLayer not yet implemented");
+}
+
 void SerializerVisitor::VisitQuantizedLstmLayer(const armnn::IConnectableLayer* layer,
                                                 const armnn::QuantizedLstmInputParams& params,
                                                 const char* name)