Support for OAuth2

[buremba]

Thanks for this great extension! This seems like a great "extension interface" for high-level programming languages such as Python & Typescript to develop DuckDB extensions.

I was looking into the authentification, and it looks like we need to pass a token as part of the secret. Could this be automated in a way similar to how Gsheets and Motherduck extensions work as follows?

1. The user runs the following query:

CREATE SECRET airport_hello_world (
      type airport,
      scope 'grpc+tls://server.example.com/'
);

2. Airport extension asking the Flight server for an external URL to authenticate the user and redirect the user (or asking for auth key to be entered manually) to the redirect_uri. Once the token is generated with, we can generate the bearer token via exchanging tokenand use it to auth the user for subsequent requests.

[rustyconover]

Hi @buremba,

Thanks for filing this issue. I'm familiar somewhat with OAuth2, but I'll review Motherduck and GSheet's implementations in their extensions and reply.

Rusty