Automatically purge old keyrings from /etc/apt/keyrings

[pschichtel]

Use Case

When creating keyrings through apt::source' key parameter there doesn't seem to be a way to automatically cleanup built-in to the apt module, so keyrings are left behind when removing sources.

Describe the Solution You Would Like

Managing the directory and having a purge option as done for apt.conf.d and friends.

Describe Alternatives You've Considered

none

[pschichtel]

I can open a PR if my suggestion is acceptable

[kenyon]

This would be a good enhancement.