There is no way to update the model LBPHFaceRecognizer

Hey. I do not have static photos, I want to train the model dynamically. So I need a method **update**.
In the original **opencv_contrib**, this method is present:
https://github.com/kyamagu/mexopencv/blob/master/opencv_contrib/%2Bcv/LBPHFaceRecognizer.m#L306

```
const lbph = new cv.LBPHFaceRecognizer()
lbph.update([resizeFaceImage], [0])
```

TypeError: lbph.update is not a function

Start at the LBPHFaceRecognizer binding and compare its exposed methods with the OpenCV contrib LBPHFaceRecognizer.m reference linked in the issue. Verify that the JavaScript example can call update with images and labels, and add or run coverage for that call if the repository has a matching test.

Written by the indexing model from the issue text.