Alias `typing` (stdlib) in `cv2/__init__.pyi` and explicitely re-export `cv2.typing`

[Avasam]

System Information

OpenCV python version: 4.8.1.78
Operating System / Platform: Windows 10
Python version: 3.9.13

Detailed description

Aliasing typing (stdlib) in cv2/__init__.pyi works around python/mypy#16216 and fixes opencv/opencv-python#901
And allow type checkers to see that the typing symbol in cv2 at runtime is actually cv2.typing.

It would look something like that:

import typing as _typing
from cv2 import typing as typing

Steps to reproduce

See opencv/opencv-python#901

import cv2
import cv2.typing

_ = cv2.typing.MatLike

and:

import cv2

_ = cv2.typing.MatLike

test with both pyright and mypy

Issue submission checklist

• I report the issue, it's not a question
• I checked the problem with documentation, FAQ, open issues, forum.opencv.org, Stack Overflow, etc and have not found any solution
• I updated to the latest OpenCV version and the issue is still there
• There is reproducer code and related data files (videos, images, onnx, etc)