Merge pull request #28615 from Kumataro:fix28606

imgcodecs(png): support cICP metadata for imreadWithMetadata() #28615

Close https://github.com/opencv/opencv/issues/28606
Related https://github.com/opencv/opencv/pull/27741 (support for imwriteWithMetadata)

### 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.
- [ ] The feature is well documented and sample code can be built with the project CMake

modules/imgcodecs/src/grfmt_png.cpp

@@ -684,6 +684,20 @@ bool  PngDecoder::readData( Mat& img )
                 m_exif.parseExif(exif, num_exif);
             }
 #endif
+#ifdef PNG_cICP_SUPPORTED
+            png_byte prim_id, tran_id, matrix_id, video_full_range_flag;
+            if (png_get_cICP(m_png_ptr, m_info_ptr, &prim_id, &tran_id, &matrix_id, &video_full_range_flag))
+            {
+                uint8_t cicp_data[4] = {
+                    static_cast<uint8_t>(prim_id),
+                    static_cast<uint8_t>(tran_id),
+                    static_cast<uint8_t>(matrix_id),
+                    static_cast<uint8_t>(video_full_range_flag)
+                };
+                auto& out = m_metadata[IMAGE_METADATA_CICP];
+                out.insert(out.end(), cicp_data, cicp_data + 4);
+            }
+#endif
 
             result = true;
         }