Improve Visual Studio Code quickstart guide

[rawwar]

Body

Something similar to what's done for PyCharm in - #48213 and #47184

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.

[rawwar]

Any ideas on how to make Airflow dev experience on VSCode better are welcome

[insomnes]

It is not directly for VS Code but pylance / pyright related. Generation of config json with the desired extra paths for tests may be automated somewhat the same way as for jetbrais IDEs, I believe: #47096