Fix clahe build

[jmackay2]

Pull Request Readiness Checklist

Fix the build related to this PR. This inherits from CLAHE, so the setBitShift and getBitShift functions need to be defined.

Error this fixes:

error: invalid new-expression of abstract class type '{anonymous}::CLAHE_Impl'
opencv/contrib/modules/cudaimgproc/src/histogram.cpp:150:11: note: because the following virtual functions are pure within '{anonymous}::CLAHE_Impl':
    class CLAHE_Impl : public cv::cuda::CLAHE
In file included from opencv_contrib/modules/cudaimgproc/include/opencv2/cudaimgproc.hpp:51
opencv/modules/imgproc/include/opencv2/imgproc.hpp:1074:26: note: 'virtual void cv::CLAHE::setBitShift(int)'
    CV_WRAP virtual void setBitShift(int bitShift) = 0;
opencv/modules/imgproc/include/opencv2/imgproc.hpp:1080:25: note: 'virtual int cv::CLAHE::getBitShift() const'
    CV_WRAP virtual int getBitShift() const = 0;

This change was tested on Ubuntu 24.04 with the latest updates from the opencv and opencv_contrib repositories. This resulted in the build being successful.

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• 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