Merge pull request #25691 from redhecker:gifSupport

[GSoC] Add GIF decode and encode for imgcodecs #25691

this is related to #24855 

we add  gif support for `imread`, `imreadmulti`, `imwrite` and `imwritemulti`

opencv_extra: https://github.com/opencv/opencv_extra/pull/1203

### 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

cmake/OpenCVFindLibsGrfmt.cmake

@@ -371,6 +371,11 @@ if(WITH_GDCM)
   endif()
 endif()
 
+if(WITH_IMGCODEC_GIF)
+  set(HAVE_IMGCODEC_GIF ON)
+elseif(DEFINED WITH_IMGCODEC_GIF)
+  set(HAVE_IMGCODEC_GIF OFF)
+endif()
 if(WITH_IMGCODEC_HDR)
   set(HAVE_IMGCODEC_HDR ON)
 elseif(DEFINED WITH_IMGCODEC_HDR)