libpng upgrade to 1.6.45 and cICP metadata support for PNG imwrite #27741
### Pull Request Readiness Checklist
resolves#24185
libpng docs: https://www.w3.org/TR/png-3/#cICP-chunk
similar code from ffmpeg: a700f0f72d/libavcodec/pngenc.c (L452-L456)
So issue #24185 can be solved by replacing `cv.imwrite` in user's code to `cv.imwriteWithMetadata`:
```python
cv.imwriteWithMetadata("frame.png", frame, [cv.IMAGE_METADATA_CICP], np.array([[9, 18, 0, 1]], np.uint8))
```
```
$ exiftool /home/d.kurtaev/opencv_build/frames_pr/image_38.png
ExifTool Version Number : 12.76
File Name : image_38.png
Directory : /home/d.kurtaev/opencv_build/frames_pr
File Size : 3.8 MB
File Modification Date/Time : 2025:09:02 20:48:22+03:00
File Access Date/Time : 2025:09:02 20:48:22+03:00
File Inode Change Date/Time : 2025:09:02 20:48:22+03:00
File Permissions : -rw-r--r--
File Type : PNG
File Type Extension : png
MIME Type : image/png
Image Width : 1080
Image Height : 1920
Bit Depth : 8
Color Type : RGB
Compression : Deflate/Inflate
Filter : Adaptive
Interlace : Noninterlaced
Color Primaries : BT.2020, BT.2100
Transfer Characteristics : BT.2100 HLG, ARIB STD-B67
Matrix Coefficients : Identity matrix
Video Full Range Flag : 1
Image Size : 1080x1920
Megapixels : 2.1
```
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
- [ ] 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
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