G-API: Wrap render functionality to python

* Wrap render Rect prim

* Add all primitives and tests

* Cover mosaic and image

* Handle error in pyopencv_to(Prim)

* Move Mosaic and Rect ctors wrappers to shadow file

* Use GAPI_PROP_RW

* Fix indent

original commit: 9fe49497bb

modules/python/src2/hdr_parser.py

@@ -832,6 +832,7 @@ class CppHeaderParser(object):
                     ("GAPI_EXPORTS_W_SIMPLE","CV_EXPORTS_W_SIMPLE"),
                     ("GAPI_WRAP", "CV_WRAP"),
                     ("GAPI_PROP", "CV_PROP"),
+                    ("GAPI_PROP_RW", "CV_PROP_RW"),
                     ('defined(GAPI_STANDALONE)', '0'),
                 ])