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/src2/hdr_parser.py

@@ -90,6 +90,10 @@ class CppHeaderParser(object):
             modlist.append("/IO")
             arg_str = arg_str.replace("CV_IN_OUT", "")
 
+        if "CV_WRAP_FILE_PATH" in arg_str:
+            modlist.append("/PATH")
+            arg_str = arg_str.replace("CV_WRAP_FILE_PATH", "")
+
         isarray = False
         npos = arg_str.find("CV_CARRAY")
         if npos >= 0:
@@ -627,6 +631,8 @@ class CppHeaderParser(object):
                                                              ("noArray", arg_type)]).strip()
                     if '/IO' in modlist and '/O' in modlist:
                         modlist.remove('/O')
+                    if (arg_name.lower() == 'filename' or arg_name.lower() == 'filepath') and '/PATH' not in modlist:
+                        modlist.append('/PATH')
                     args.append([arg_type, arg_name, defval, modlist])
                 npos = arg_start-1