Merge pull request #20271 from TolyaTalamanov:at/extend-python-bindings

G-API: Extend python bindings

* Extend G-API bindings

* Wrap timestamp, seqNo, seq_id
* Wrap copy
* Wrap parseSSD, parseYolo

* Rewrap cv.gapi.networks

* Add test for metabackend in pytnon

* Remove int64 pyopencv_to

modules/gapi/src/backends/common/gmetabackend.cpp

@@ -85,6 +85,19 @@ class GGraphMetaBackendImpl final: public cv::gapi::GBackend::Priv {
                          const std::vector<cv::gimpl::Data>&) const override {
         return EPtr{new GraphMetaExecutable(graph, nodes)};
     }
+
+    virtual bool controlsMerge() const override
+    {
+        return true;
+    }
+
+    virtual bool allowsMerge(const cv::gimpl::GIslandModel::Graph &,
+                             const ade::NodeHandle &,
+                             const ade::NodeHandle &,
+                             const ade::NodeHandle &) const override
+    {
+        return false;
+    }
 };
 
 cv::gapi::GBackend graph_meta_backend() {