Merge pull request #18196 from mpashchenkov:mp/garray-initialization

[G-API]: Add GArray initialization support

* Added GArray initialization (CONST_VALUE, GScalar analog) and test for this

* Whitespaces

* And one more space

* Trailing whitespace

* Test name changed. Build with magic commands.

* GArray works with rvalue initialization

* Code cleanup

* Ternary operator in the initialization list.

modules/gapi/src/compiler/gobjref.hpp

@@ -29,6 +29,7 @@ namespace gimpl
     using ConstVal = util::variant
     < util::monostate
     , cv::Scalar
+    , cv::detail::VectorRef
     >;
 
     struct RcDesc