source-postgres support azure entra authentication for service principal

[vpipkt]

In my environment, most of our teams using Postgres run Azure Database for PostgreSQL flexible server. One of the attractions to this is we can use Entra for passwordless authentication in many more settings. However when we want to replicate from these database with source-postgres today (v3.6.30), we have to use local database authentication. Our dba's don't like this. They would rather Airbyte authenticate via an Entra application registration. This means generating a short-lived token from service principal client id and client secret, which is used to connect to the database.

This is basically the same as in #50398, but toward Postgres. My goal with this issue is to get some involvement from the airbyte core team and community, as the Postgres connector is ab_internal.sl: 100 ab_internal.ql: 100.

I do have a draft PR of a working implementation, and very happy to have any feedback at all there.

[rowanmoul]

Just saw this in the connector settings page, which is amazing. Thank you for adding this!
Why not take it a step further and use Workload Identity with federated credentials though? It looks like the Helm Chart already has support for adding the necessary annotations to the service account used by airbyte's pods (as well as support for running the workload replication pods as a separate service account). All that is needed is to create a WorkloadIdentityCredential instead of a ClientSecretCredential. You could even chain the two options together so that it tries each option one after the other. I may try making a PR for this myself based on your PR.