Merge pull request #24773 from tailsu:sd/pathlike

python: accept path-like objects wherever file names are expected #24773

Merry Christmas, all 🎄

Implements #15731

Support is enabled for all arguments named `filename` or `filepath` (case-insensitive), or annotated with `CV_WRAP_FILE_PATH`.

Support is based on `PyOS_FSPath`, which is available in Python 3.6+. When running on older Python versions the arguments must have a `str` value as before.

### Pull Request Readiness Checklist

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

- [x] I agree to contribute to the project under Apache 2 License.
- [x] 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
- [x] The PR is proposed to the proper branch
- [x] 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

modules/python/test/test_pathlike.py

@@ -0,0 +1,38 @@
+from tests_common import NewOpenCVTests, unittest
+import cv2 as cv
+import os
+
+
+def import_path():
+    import sys
+    if sys.version_info[0] < 3 or sys.version_info[1] < 6:
+        raise unittest.SkipTest('Python 3.6+ required')
+
+    from pathlib import Path
+    return Path
+
+
+class CanPassPathLike(NewOpenCVTests):
+    def test_pathlib_path(self):
+        Path = import_path()
+
+        img_path = self.find_file('cv/imgproc/stuff.jpg', [os.environ.get('OPENCV_TEST_DATA_PATH')])
+
+        image_from_str = cv.imread(img_path)
+        self.assertIsNotNone(image_from_str)
+
+        image_from_path = cv.imread(Path(img_path))
+        self.assertIsNotNone(image_from_path)
+
+
+    def test_type_mismatch(self):
+        import_path() # checks python version
+
+        with self.assertRaises(TypeError) as context:
+            cv.imread(123)
+
+        self.assertTrue('str or path-like' in str(context.exception))
+
+
+if __name__ == '__main__':
+    NewOpenCVTests.bootstrap()