Merge pull request #25221 from savuor:rv/bench_3d

OBJ and PLY loaders extention to support texture coordinates and difused colors #25221

### This PR changes
* Texture coordinates support added to `loadMesh()` and `saveMesh()`
* `loadMesh()` changes its behavior: all vertex attribute arrays (vertex coordinates, colors, normals, texture coordinates) now have the same size and same-index corresponce
  - This makes sense for OBJ files where vertex attribute arrays are independent from each other and are randomly accessed when defining faces
  - Looks like this behavior may also happen in some PLY files; however, it is not implemented until we encounter such files in a wild nature
  - At the same time `loadPointCloud()` keeps its behavior and loads vertex attributes as they are given in the file
* PLY loader supports synonyms for the properties: `diffuse_red`, `diffuse_green` and `diffuse_blue` along with `red`, `green` and `blue`
* `std::vector<cv::Vec3i>` supported as an index array type
* Colors are loaded as [0, 1] floats instead of uchars
  - Since colors are usually saved as floats, internal conversion to uchar at loading significantly drops accuracy
  - Performing uchar conversion does not always makes sense and can be performed by a user if they needs it
* PLY loading fixed: wrong offset ruined x coordinate
* Python tests added for `loadPointCloud` and `loadMesh`

### 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
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

modules/3d/test/test_ptcloud_utils.cpp

@@ -94,8 +94,9 @@ void generateSphere(OutputArray sphere_pts, const vector<float> &model, float th
         // Let r change then generate thickness
         float r = i < sphere_num ? model[3] : rng.uniform(model[3] - thr, model[3] + thr);
         // Generate a random vector and normalize it.
+        // Note: these vectors are not spread uniformly across the sphere
         Vec3f vec(rng.uniform(limit[0], limit[1]), rng.uniform(limit[2], limit[3]),
-                rng.uniform(limit[4], limit[5]));
+                  rng.uniform(limit[4], limit[5]));
         float l = sqrt(vec.dot(vec));
         // Normalizes it to have a magnitude of r
         vec /= l / r;