calib3d refactoring: the light version

[vpisarev]

this is the light version of #18915. Merge together with opencv/opencv_contrib#2767.

Unlike #18915, this pull request retains all functionality from the split calib3d module in the original cv namespace, rather than cv::_3d, cv::calib and cv::stereo, respectively.

Pull Request Readiness Checklist

• 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 other license that is incompatible with OpenCV
• The PR is proposed to proper branch
• There is reference to 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

[vpisarev]

👍