#1993 but for opencv built from source

[Vivraan]

Exactly as the title suggests, refers to microsoft/vscode-python#1993.

OpenCV built with NVIDIA CUDA and cuDNN on.
VS Code: 1.47.2
OS: Windows 10 Home 1909 18363.959

Refer: microsoft/python-language-server#1926

[karthiknadig]

@SHIVAMMUKHERJEE We have recently released a new and more performant language server called Pylance. This issue will likely be addressed there. Because our team's development efforts have shifted to support the new language server, we'd encourage you to try it out. You can download Pylance from the marketplace and install it alongside the core Python extension.

[jakebailey]

Dupe of #138; this code is compiled and currently requires a stub.