[Feature] Add way to delete "old" publications

**Packages**

Media

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

N/A

**Describe the solution you'd like**

Over time the space being used for publications will grow. Likely anything older than the current is never going to be used again so can be removed if desired.

We should add an option in settings to Delete Older Publications which does this.

**Describe alternatives you've considered**

Deleting everything.

**Additional context**

N/A

The issue names the Media package and a settings option for deleting older publications. Start by locating the settings implementation and publication deletion or storage entry points; clarify how “older” and “current” are defined. Done means the option safely removes only the intended publications and is covered by the project’s relevant tests.

Written by the indexing model from the issue text.