Add declarative configuration to define custom roles

Description

Add declarative configuration to define custom roles in either airflow.cfg or webserver_config.py.

Use case/motivation

Currently the only way to define custom roles is through the CLI or UI. This isn't ideal for those deploying configuration through a repository (e.g., GitOps).

It seems like this feature is already possible with webserver_config.py, however not documented here. If so, I will change the request... https://airflow.apache.org/docs/apache-airflow/stable/security/webserver.html

Related issues

No response

Are you willing to submit a PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct