Merge pull request #18332 from TolyaTalamanov:at/wrap-GIn-GOut

[G-API] Wrap GIn & GOut

* Wrap GIn & GOut into python

* Remove extra brackets

* Use reinterpret_cast

modules/gapi/include/opencv2/gapi/gcomputation.hpp

@@ -161,8 +161,8 @@ public:
      *
      * @sa @ref gapi_data_objects
      */
-    GComputation(GProtoInputArgs &&ins,
-                 GProtoOutputArgs &&outs);             // Arg-to-arg overload
+    GAPI_WRAP GComputation(GProtoInputArgs &&ins,
+                           GProtoOutputArgs &&outs);             // Arg-to-arg overload
 
     // 2. Syntax sugar and compatibility overloads
     /**

modules/gapi/include/opencv2/gapi/gproto.hpp

@@ -57,6 +57,8 @@ template<class Tag>
 struct GIOProtoArgs
 {
 public:
+    // NB: Used by python wrapper
+    GIOProtoArgs() = default;
     explicit GIOProtoArgs(const GProtoArgs& args) : m_args(args) {}
     explicit GIOProtoArgs(GProtoArgs &&args)      : m_args(std::move(args)) {}