IVGCVSW-4210 Create a public API for the common backend files

 * Create a public API for the common backend files
 * Move OutputHandler to armnn internal
 * Remove unused headers

Signed-off-by: Matteo Martincigh <matteo.martincigh@arm.com>
Signed-off-by: Narumol Prangnawarat <narumol.prangnawarat@arm.com>
Change-Id: I3e86d908b021e3561befa9d45158d87d2cbb18c0
diff --git a/src/backends/backendsCommon/WorkloadData.hpp b/src/backends/backendsCommon/WorkloadData.hpp
index 6a96a4a..43be3cd 100644
--- a/src/backends/backendsCommon/WorkloadData.hpp
+++ b/src/backends/backendsCommon/WorkloadData.hpp
@@ -4,7 +4,8 @@
 //
 #pragma once
 
-#include "CpuTensorHandleFwd.hpp"
+#include <armnn/backends/CpuTensorHandleFwd.hpp>
+#include <armnn/backends/ITensorHandle.hpp>
 
 #include <InternalTypes.hpp>
 
@@ -14,7 +15,6 @@
 #include <armnn/Types.hpp>
 #include <armnn/Tensor.hpp>
 
-#include <backendsCommon/OutputHandler.hpp>
 #include <backendsCommon/WorkloadInfo.hpp>
 
 namespace armnn