IVGCVSW-3029 Remove any AddLayer capabilities from SubgraphView

 * Removed the reference to the parent graph in SubgraphView
 * Removed the AddLayer method in SubgraphView
 * Updated the code where necessary to adapt to the new changes in
   SubgraphView
 * Fixed a check in the CreatePreCompiledWorkloadTest test function

Change-Id: I4d3af87f11ec3cd8f18a21b250a2d295da56e1a0
Signed-off-by: Matteo Martincigh <matteo.martincigh@arm.com>
diff --git a/src/backends/backendsCommon/IBackendInternal.hpp b/src/backends/backendsCommon/IBackendInternal.hpp
index 108e66e..d23209e 100644
--- a/src/backends/backendsCommon/IBackendInternal.hpp
+++ b/src/backends/backendsCommon/IBackendInternal.hpp
@@ -43,6 +43,7 @@
 
     using ISubgraphViewConverterPtr = std::unique_ptr<ISubgraphViewConverter>;
 
+    using GraphUniquePtr = std::unique_ptr<Graph>;
     using SubgraphViewUniquePtr = std::unique_ptr<SubgraphView>;
 
     virtual IMemoryManagerUniquePtr CreateMemoryManager() const = 0;