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/RefArgMinMaxWorkload.hpp b/src/backends/reference/workloads/RefArgMinMaxWorkload.hpp
index 97b7077..df9ebca 100644
--- a/src/backends/reference/workloads/RefArgMinMaxWorkload.hpp
+++ b/src/backends/reference/workloads/RefArgMinMaxWorkload.hpp
@@ -16,6 +16,10 @@
     explicit RefArgMinMaxWorkload(const ArgMinMaxQueueDescriptor& descriptor,
                                   const WorkloadInfo& info);
 
-    virtual void Execute() const override;
+    void Execute() const override;
+    void ExecuteAsync(WorkingMemDescriptor& workingMemDescriptor)  override;
+
+private:
+    void Execute(std::vector<ITensorHandle*> inputs, std::vector<ITensorHandle*> outputs) const;
 };
 } //namespace armnn
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