IVGCVSW-3539 Add CL support and tests for Stack

* Added CL backend support for Stack
* Added unit tests for Stack on the CL backend
* Refactored unit tests to support generic data types

Signed-off-by: Matthew Jackson <matthew.jackson@arm.com>
Change-Id: I38ee3e9d8947ea98a3104c982698001e704d7d89
diff --git a/src/backends/cl/workloads/ClWorkloads.hpp b/src/backends/cl/workloads/ClWorkloads.hpp
index a64dea2..03dffc4 100644
--- a/src/backends/cl/workloads/ClWorkloads.hpp
+++ b/src/backends/cl/workloads/ClWorkloads.hpp
@@ -36,6 +36,7 @@
 #include "ClSpaceToBatchNdWorkload.hpp"
 #include "ClSpaceToDepthWorkload.hpp"
 #include "ClSplitterWorkload.hpp"
+#include "ClStackWorkload.hpp"
 #include "ClStridedSliceWorkload.hpp"
 #include "ClSubtractionWorkload.hpp"
 #include "ClConvertFp16ToFp32Workload.hpp"