Support for Azure AD Authentication using tljh-config command

[arun-soliton]

Proposed change

Currently for Jupyterhub (tljh), there is a this tljh-config command to setup authentication for GitHub, Google and AWS in the documentation given here https://tljh.jupyter.org/en/latest/howto/auth/github.html.

By following the same step, I was not able to setup authentication for Azure AD. Additionally it shows Bad Gateway which I have reported as a bug in #950 and I am not sure whether is this supported or not.

1. If it already supported a clear documentation on this would be helpful for setting the authentication for JupyterHub (tljh) using Azure AD.
2. If it is not supported, can this be a feature-request?

(Optional): Suggest a solution

1. Want to go through how exactly tljh-config works and need to figure out the same steps followed for configuring authentication and come up with a similar solution.