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/misc/python/package/gapi/__init__.py

@@ -11,11 +11,36 @@ def register(mname):
     return parameterized
 
 
+@register('cv2.gapi')
+def networks(*args):
+    return cv.gapi_GNetPackage(list(map(cv.detail.strip, args)))
+
+
 @register('cv2.gapi')
 def compile_args(*args):
     return list(map(cv.GCompileArg, args))
 
 
+@register('cv2')
+def GIn(*args):
+    return [*args]
+
+
+@register('cv2')
+def GOut(*args):
+    return [*args]
+
+
+@register('cv2')
+def gin(*args):
+    return [*args]
+
+
+@register('cv2.gapi')
+def descr_of(*args):
+    return [*args]
+
+
 @register('cv2')
 class GOpaque():
     # NB: Inheritance from c++ class cause segfault.