Merge pull request #21782 from TolyaTalamanov:at/fix-1d-mat-problems

[G-API] Fix problems with 1D cv::Mat as graph output

* Fix issues with 1D cv::Mat

* Fix cv::Mat::create

* Fix standalone build

* Add test on 1d mat

* Fix warning

* Add additional condition

* Add more tests

modules/gapi/src/api/gbackend.cpp

@@ -411,6 +411,12 @@ void createMat(const cv::GMatDesc &desc, cv::Mat& mat)
     {
         GAPI_Assert(!desc.planar);
         mat.create(desc.dims, desc.depth);
+#if !defined(GAPI_STANDALONE)
+        // NB: WA for 1D mats.
+        if (desc.dims.size() == 1u) {
+            mat.dims = 1;
+        }
+#endif
     }
 }