Introduce a new abstraction layer over island input/output data

- Port GExecutor to this new interface

modules/gapi/src/backends/fluid/gfluidbackend.hpp

@@ -153,6 +153,8 @@ public:
     virtual void run(std::vector<InObj>  &&input_objs,
                      std::vector<OutObj> &&output_objs) override;
 
+    using GIslandExecutable::run; // (IInput&, IOutput&) version
+
     void run(std::vector<InObj>  &input_objs,
              std::vector<OutObj> &output_objs);