IVGCVSW-3231 Add reference workload support for SpaceToDepth

* Added reference workload for SpaceToDepth
* Added unit tests for float32 & uint8
* Minor sort refactoring to RefWorkloads.hpp to alphabetical order

Change-Id: I2e01f8101650e2aae102a8a32bc0064f067141ab
Signed-off-by: Keith Davis <keith.davis@arm.com>
diff --git a/src/backends/reference/backend.mk b/src/backends/reference/backend.mk
index a430f4f..6b7e895 100644
--- a/src/backends/reference/backend.mk
+++ b/src/backends/reference/backend.mk
@@ -58,11 +58,13 @@
         workloads/RefRsqrtWorkload.cpp \
         workloads/RefSoftmaxWorkload.cpp \
         workloads/RefSpaceToBatchNdWorkload.cpp \
+        workloads/RefSpaceToDepthWorkload.cpp \
         workloads/RefStridedSliceWorkload.cpp \
         workloads/RefSplitterWorkload.cpp \
         workloads/ResizeBilinear.cpp \
         workloads/Rsqrt.cpp \
         workloads/SpaceToBatchNd.cpp \
+        workloads/SpaceToDepth.cpp \
         workloads/StridedSlice.cpp \
         workloads/StringMapping.cpp \
         workloads/Softmax.cpp \