Merge pull request #25551 from Kumataro:fix25550

highgui: wayland: fix to pass highgui test #25551

Close #25550

- optimize Mat to XRGB8888 conversion with OpenCV functions
  - extend to support CV_8S/16U/16S/32F/64F
  - extend to support 1/4 channels
- fix to update value timing
 - initilize slider_ value if value is not nullptr.
 - Update user-ptr value and call on_change() function if cv_wl_trackbar::draw() is not called.
- Update usage of WAYLAND/XDG macro to avoid reference undefined macro.
- Update documents

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

modules/highgui/test/test_gui.cpp

@@ -48,6 +48,16 @@ inline void verify_size(const std::string &nm, const cv::Mat &img)
 {
     EXPECT_NO_THROW(imshow(nm, img));
     EXPECT_EQ(-1, waitKey(200));
+
+    // see https://github.com/opencv/opencv/issues/25550
+    // Wayland backend is not supported getWindowImageRect().
+    string framework;
+    EXPECT_NO_THROW(framework = currentUIFramework());
+    if(framework == "WAYLAND")
+    {
+       return;
+    }
+
     Rect rc;
     EXPECT_NO_THROW(rc = getWindowImageRect(nm));
     EXPECT_EQ(rc.size(), img.size());