Features2d cleanup: Move several feature detectors and descriptors to opencv_contrib #25292
features2d cleanup: #24999
The PR moves KAZE, AKAZE, AgastFeatureDetector, BRISK and BOW to opencv_contrib/xfeatures2d.
Related PR: opencv/opencv_contrib#3709
* Implement ASIFT in C++
* '>>' should be '> >' within a nested template
* add a sample for asift usage
* bugfix empty keypoints cause crash
* simpler initialization for mask
* suppress the number of lines
* correct tex document
* type casting
* add descriptorsize for asift
* smaller testdata for asift
* more smaller test data
* add OpenCV short license header