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/WorkloadFactory.cpp b/src/backends/backendsCommon/WorkloadFactory.cpp
index 9901dcb..1d4ed7e 100644
--- a/src/backends/backendsCommon/WorkloadFactory.cpp
+++ b/src/backends/backendsCommon/WorkloadFactory.cpp
@@ -3,9 +3,6 @@
 // SPDX-License-Identifier: MIT
 //
 
-#include "CpuTensorHandle.hpp"
-#include "WorkloadFactory.hpp"
-
 #include <Layer.hpp>
 #include <LayersFwd.hpp>
 
@@ -15,7 +12,10 @@
 #include <armnn/BackendRegistry.hpp>
 
 #include <backendsCommon/WorkloadFactory.hpp>
-#include <backendsCommon/IBackendInternal.hpp>
+#include <armnn/backends/IBackendInternal.hpp>
+#include <backendsCommon/CpuTensorHandle.hpp>
+#include <backendsCommon/WorkloadFactory.hpp>
+
 #include <backendsCommon/test/WorkloadTestUtils.hpp>
 
 #include <boost/cast.hpp>