Feature review pre-migration of Drupal functionality

The API is now available on staging for testing and validation. Below are some sample URLs available from the endpoint, with all options denoted in the openapi.yaml file in the repository.

https://api-staging.eclipse.org/mailing_lists/
https://api-staging.eclipse.org/mailing_lists/gendoc-dev
https://api-staging.eclipse.org/mailing_lists/projects
https://api-staging.eclipse.org/mailing_lists/projects/modeling.gendoc

Please let me know if there are any missing features!