Repository: opencv
Issue: Clean samples
Labels: feature,cleanup

### Describe the feature and motivation

samples is one of the main faces of the library. Currently, we have a lot of poorly organized, mainly obsolete samples in OpenCV. We need to clean it up in OpenCV 5 and maybe even in OpenCV 4.

* **C++ samples**:
  * bgfg_segm.cpp - old and low-quality
  * camshiftdemo.cpp - old and low-quality. Deep-learning based object detection and tracking demos can be used instead
  * cloning_demo and cloning_gui - low-quality. Deep-learning based computational photography demos could be added later.
  * contours2.cpp, convexhull.cpp - old. can easily be removed. Example how to call convexHull can be added to documentation.
  * create_mask.cpp is almost useless example. can be removed.
  * dbt_face_detection.cpp - obsolete
  * delaunay2 - obsolete. Delaunay triangulation might still be useful, but it's quite stupid way to demonstrate it.
  * demhist - we can retain it, but it shall definitely be improved. For now we can keep it as-is.
  * detect_blob - too specialized. Can be removed.
  * detect_mser - possibly retain, but make more useful.
  * dft - too artificial example. Can be removed.
  * digits_lenet - keep, but make it more entertaining, let user to draw digits with mouse.
  * digits_svm - remove
  * dis_opticalflow - remove. We now support RAFT deep learning model.
  * distrans - keep, but need to improve.
  * drawing - keep, but need to significantly improve.
  * edge - we can retain it if we demonstrate many different methods, including deep learning based.
  * ela - looks almost useless. remove
  * em - demo for ML. move to opencv_contrib.
  * epipilar_lines - remove it in favor of essential_mat_reconstr
  * facedetect - remove in favor of deep learning-based demo
  * facial_features - remove in favor of deep learning-based demo
  * falsecolor - probably keep for now, improve later
  * fback - another old demo of optical flow. Remove in favor of deep learning-based demo
  * ffilldemo - we can keep it as long as it's more educative. There should be a gallery of special sample images.
  * filestorage - can be kept, but should be improved
  * fitellipse - looks nice. probably can be kept and extended to demonstrate other figures like convex hull etc.
  * flann_search_dataset - remove it. Probably should have face recognition demo (or place recognition demo) instead.
  * ... (skip several)
  * inpaint - remove. Need to replace it with deep learning-based demo.
  * kalman - remove. We already have very fast deep-learning based trackers
  * kmeans - too primitive. Remove.
  * laplace - too primitive. Remove.
  * letter_recog - remove in favor of deep learning-based demo working with real images.
  * lkdemo - classic. Keep it for now, but we need a better point tracking algorithm and demo. Something like PTAM.
  * logistic_regression - move to opencv_contrib/ml/samples.
  * lsd_lines - remove. Add deep learning-based demo as soon as we have such an algorithm.
  * mask_tmpl - remove.
  * matchmethod_orb_... - remove. It's enough to have planar object tracking demo using SIFT/A-SIFT.
  * minarea - too primitive, remove.
  * morphology2 - entertaining but primitive. May be kept, but should be improved. E.g. it can be converted to object counting demo.
  * neural_network - it's obsolete. remove.
  * npr_demo - keep and improve.
  * pca - somewhat old, but might be useful for education purposes. Can keep, but need to be improved.
  * peopledetect - remove in favor of deep learning-based demo.
  * phase_corr - remove
  * points_classifier - move to opencv_contrib/ml/samples
  * polar_transforms - remove perhaps
  * segment_objects -  replace with a demo of SAM or a similar model.
  * simd_basic - may keep, but needs to be extended perhaps to demonstrate more useful stuff.
  * smile_detect - remove. The feature (smile detection) would be a useful addition to the deep learning-based face detection example.
  * squares - too old. remove.
  * stereo_calib - keep, but probably improve.
  * stereo_match - same.
  * stitching_detailed and stitching - good demos, but need improvements. Do we need 2 variants of image stitching demo?
  * text_skeweness_correction - remove. replace with text detection and recognition demo.
  * train_HOG - obsolete. Remove.
  * train_svmsgd - move to opencv_contrib/ml/samples.
  * travelsalesman - move to opencv_contrib/ml/samples.
  * tree_engine - same.
  * video_capture_* - combine multiple examples into 1-3 examples. For example, conventional 2D capture and 3D capture (using depth sensor).
  * warpperspective_demo - remove. Probably, we need a demo of various image augmentations using OpenCV.
  * watershed - probably, keep or combine with grabcut demo.
* **Python samples**:
  *  Python samples are generally better, but need to remove obsolete demos, demos for ML or simple demos which are duplicates of C++ samples.
* **DNN  samples**:
  * Mostly they are fine, but we can consolidate text detection/recognition examples and also merge "tf_" examples into the respective examples for ONNX (since ONNX is now our main format). 
* do we need dedicated "java/" if we have "android/"?
* winrt, winrt_universal and wp8 should probably be removed
* example of HAL should be non-trivial. We need to polish Carotene, we need to move IPP-based HAL from 'embedded HAL' to 3rdparty. They will be much more realistic examples for HAL than opencv/samples/hal.
* openvx shall be removed, we no longer support it.
* probably, put directx, opengl, sycl, va_intel, opencl under "interoperability" directory. Are they all still relevant?
* since non-CPU HAL and, correspondingly, UMat, will evolve, tapi and gpu samples could probably be put to cpp/python directories.



### Additional context

_No response_