Post-publish hook

Is your feature request related to a problem? Please describe.

We are part of the packages.microsoft.com team and want a more optimal way to clear certain files from our Content Delivery Network when we publish new when publishing new content

Describe the solution you'd like

We would like a script to clear out the cache in our CDN anytime new content is published so we are able to resolve those cache issues. We would want a post-publish hook to run a script and this is most likely where the place should be in the code https://github.com/pulp/pulpcore/blob/00c885db9d866274562fd2621a23381422602f62/pulpcore/app/models/publication.py#L204

Describe alternatives you've considered

The current solution we are working on is having to monitor the publish tasks and wait for one to complete before clearing files from the CDN cache service.

Read pulpcore/app/models/publication.py around line 204 to understand the publication flow and where a post-publish hook could run. Check the existing publication task behavior and determine what completion should expose for running a CDN cache-clearing script after new content is published.