Merge pull request #25986 from asmorkalov:as/js_for_contrib

Split Javascript white-list to support contrib modules #25986

Single whitelist converted to several per-module json files. They are concatenated automatically and can be overriden by user config.

Related to https://github.com/opencv/opencv/pull/25656

### 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
- [ ] 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

platforms/js/build_js.py

@@ -256,8 +256,7 @@ if __name__ == "__main__":
     parser.add_argument('--build_flags', help="Append Emscripten build options")
     parser.add_argument('--build_wasm_intrin_test', default=False, action="store_true", help="Build WASM intrin tests")
     # Write a path to modify file like argument of this flag
-    parser.add_argument('--config', default=os.path.join(os.path.dirname(os.path.abspath(__file__)), 'opencv_js.config.py'),
-                        help="Specify configuration file with own list of exported into JS functions")
+    parser.add_argument('--config', help="Specify configuration file with own list of exported into JS functions")
     parser.add_argument('--webnn', action="store_true", help="Enable WebNN Backend")
 
     transformed_args = ["--cmake_option=%s".format(arg) if arg[:2] == "-D" else arg for arg in sys.argv[1:]]
@@ -265,7 +264,8 @@ if __name__ == "__main__":
 
     log.debug("Args: %s", args)
 
-    os.environ["OPENCV_JS_WHITELIST"] = os.path.abspath(args.config)
+    if args.config is not None:
+        os.environ["OPENCV_JS_WHITELIST"] = os.path.abspath(args.config)
 
     if 'EMMAKEN_JUST_CONFIGURE' in os.environ:
         del os.environ['EMMAKEN_JUST_CONFIGURE']  # avoid linker errors with NODERAWFS message then using 'emcmake' launcher