IVGCVSW-6856 Add GATHERNd FrontEnd and Ref Implementation

* Add front end
* Add reference workload
* Add unit tests
* Add EndToEnd test

Signed-off-by: Teresa Charlin <teresa.charlinreyes@arm.com>
Change-Id: I4cebd17b18476df86162e2dda3366c10e80bd2f8
diff --git a/src/backends/reference/RefLayerSupport.hpp b/src/backends/reference/RefLayerSupport.hpp
index b787d25..98770ad 100644
--- a/src/backends/reference/RefLayerSupport.hpp
+++ b/src/backends/reference/RefLayerSupport.hpp
@@ -169,6 +169,11 @@
                                    const FullyConnectedDescriptor& descriptor,
                                    Optional<std::string&> reasonIfUnsupported = EmptyOptional()) const override;
 
+    bool IsGatherNdSupported(const TensorInfo& input0,
+                             const TensorInfo& input1,
+                             const TensorInfo& output,
+                             Optional<std::string&> reasonIfUnsupported = EmptyOptional()) const;
+
     bool IsGatherSupported(const TensorInfo& input0,
                            const TensorInfo& input1,
                            const TensorInfo& output,