Refactor Forced Import

 * Find and replace all workloads associated with imported IO
 * Only attempt tensorhandle replacement if supported by all workloads
 * Add new RefBaseWorkload to enable forced input for ref backend
 * Store imported tensorhandles in preImportedTensorhandles instead of outputHandles
 * Create pre-imported tensorhandles at network load-time
 * Front load import workload validation to load network time
 * Only call ReplaceTensorHandle when needed

Change-Id: I3816a71b7f57ae90388bb16462a75d4ef3544fa7
Signed-off-by: Finn Williams <finn.williams@arm.com>
diff --git a/src/backends/cl/workloads/ClConvolution2dWorkload.hpp b/src/backends/cl/workloads/ClConvolution2dWorkload.hpp
index 891d509..e4177e4 100644
--- a/src/backends/cl/workloads/ClConvolution2dWorkload.hpp
+++ b/src/backends/cl/workloads/ClConvolution2dWorkload.hpp
@@ -40,6 +40,8 @@
 
     arm_compute::ConvolutionMethod GetConvolutionMethod() const;
 
+    bool SupportsTensorHandleReplacement() const override { return true;};
+
 protected:
     void Reconfigure() override;