ximgproc: add hole filling for run-length encoded images

[yuchangminghit]

This PR introduces a new function fillHoles() to the run-length morphology module:

• Adds hole filling capability for run-length encoded binary images
• Supports both 4 and 8 connectivity options

Pull Request Readiness Checklist

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

• I agree to contribute to the project under Apache 2 License.
• 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
• The PR is proposed to the proper branch
• 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.
• The feature is well documented and sample code can be built with the project CMake

[yuchangminghit]

Hi @asmorkalov , gentle reminder on the RLE hole filling PR. Ready for review.

[yuchangminghit]

Hi @asmorkalov , gentle ping. I’m really hoping to contribute this hole-filling function to the run-length morphology component in the ximgproc module, as I believe it would be a useful addition.

Regarding the CI status: I checked the logs and the failures appear to be due to network timeouts . This suggests it’s not a code issue. If possible, could you help trigger a re-run of the CI checks?

I’m very interested in getting this feature into opencv_contrib and am ready to make any needed adjustments. Thank you for your time.

[asmorkalov]

Could you update the PR to trigger new CI iteration (e.g. rebase on top of current 4.x)

[yuchangminghit]

Could you update the PR to trigger new CI iteration (e.g. rebase on top of current 4.x)

Thank you for the reminder.
I have rebased the PR onto the latest 4.x branch. The default CI checks have passed successfully.