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/backend.mk b/src/backends/reference/backend.mk
index 33e161c..d9a5a1d 100644
--- a/src/backends/reference/backend.mk
+++ b/src/backends/reference/backend.mk
@@ -73,6 +73,7 @@
         workloads/RefFillWorkload.cpp \
         workloads/RefFloorWorkload.cpp \
         workloads/RefFullyConnectedWorkload.cpp \
+        workloads/RefGatherNdWorkload.cpp \
         workloads/RefGatherWorkload.cpp \
         workloads/RefInstanceNormalizationWorkload.cpp \
         workloads/RefL2NormalizationWorkload.cpp \