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/test/OptimizationViewsTests.cpp b/src/backends/backendsCommon/test/OptimizationViewsTests.cpp
index 67c3e2c..5474f5d 100644
--- a/src/backends/backendsCommon/test/OptimizationViewsTests.cpp
+++ b/src/backends/backendsCommon/test/OptimizationViewsTests.cpp
@@ -8,7 +8,7 @@
 #include <Graph.hpp>
 #include <SubgraphView.hpp>
 #include <SubgraphViewSelector.hpp>
-#include <backendsCommon/OptimizationViews.hpp>
+#include <armnn/backends/OptimizationViews.hpp>
 #include <Network.hpp>
 
 #include "CommonTestUtils.hpp"