Webhook service

As an NGI team member, I want a generic server that runs all sorts of cron jobs to sync data from foreign APIs, or triggers web hooks, so we may as well set up one right now. 

 _Originally posted by @fricklerhandwerk in [#496](https://github.com/ngi-nix/ngipkgs/issues/496#issuecomment-2654626320)_

Relevant: https://github.com/ngi-nix/forge/issues/801