IVGCVSW-5815 Generalise ConstCpuTensorHandle

* Generalises ConstCpuTensorHandle and inherited
  classes by removing 'Cpu' from aliases.
* New renamed classes: ConstTensorHandle, TensorHandle,
  ScopedTensorHandle, PassthroughTensorHandle,
  ConstPassthroughTensorHandle.

Signed-off-by: James Conroy <james.conroy@arm.com>
Change-Id: I1824e0e134202735fb77051f20a7252f161dfe16
diff --git a/src/armnn/Layer.hpp b/src/armnn/Layer.hpp
index d43545c..76f9b41 100644
--- a/src/armnn/Layer.hpp
+++ b/src/armnn/Layer.hpp
@@ -200,7 +200,7 @@
 inline IOutputSlot* InputSlot::GetConnection() { return GetConnectedOutputSlot(); }
 
 
-class ScopedCpuTensorHandle;
+class ScopedTensorHandle;
 
 // Base layer class
 
@@ -391,7 +391,7 @@
     LayerType* CloneBase(Graph& graph, Params&& ... params) const;
 
     // Retrieve the Handles to the constants
-    using ConstantTensors = std::vector<std::reference_wrapper<std::shared_ptr<ConstCpuTensorHandle>>>;
+    using ConstantTensors = std::vector<std::reference_wrapper<std::shared_ptr<ConstTensorHandle>>>;
     virtual ConstantTensors GetConstantTensorsByRef() {return ConstantTensors(); };
 
     // "Blob"