IVGCVSW-5787 Add/Update Execute() implementations in RefActivationWorkload

 * Added multithreaded StridedSliceEndToEndTest

Signed-off-by: Finn Williams <Finn.Williams@arm.com>
Change-Id: I4579db7b5959e0a22256f1bda00238c22e611dec
diff --git a/src/backends/reference/workloads/RefDebugWorkload.hpp b/src/backends/reference/workloads/RefDebugWorkload.hpp
index d7e3cd9..d0c47dd 100644
--- a/src/backends/reference/workloads/RefDebugWorkload.hpp
+++ b/src/backends/reference/workloads/RefDebugWorkload.hpp
@@ -30,10 +30,12 @@
     using TypedWorkload<DebugQueueDescriptor, DataType>::TypedWorkload;
 
     void Execute() const override;
+    void ExecuteAsync(WorkingMemDescriptor& workingMemDescriptor)  override;
 
     void RegisterDebugCallback(const DebugCallbackFunction& func) override;
 
 private:
+    void Execute(std::vector<ITensorHandle*> inputs) const;
     DebugCallbackFunction m_Callback;
 };