Add action hook after cron processed it's jobs

[tott]

Sometimes it's hard to debug cron jobs or validate the results. A simple action fired after the wp-cron.php did his magic could help improve this experience.

Add action hook to wp-cron.php

#22143 was marked as a duplicate.

I guess using the 'shutdown' hook wouldn't do, since you would want access to the jobs just completed.

How about calling the hook 'did_cron' instead?

Added patch from #22143; it fires the action immediately after the event has executed and passes in some args specific to that event.