Cyphers/exec can create tensors (#3445) (#3462)

* Add method to check if an Executable can create tensors

* Add a Backend check to see if Executable can create tensors

* Update per review comment

* style

* Possible fix so that backend does not keep holding on to the dummy ng_exec

src/ngraph/runtime/backend.cpp

@@ -169,5 +169,6 @@ bool runtime::Backend::executable_can_create_tensors()
     catch (...)
     {
     }
+    remove_compiled_function(exec);
     return exec_can_create_tensors;
 }