oxlog: want a way to list N most recent log files

When debugging, log rotation may have occurred at some point during the event of interest. In that case, it's often useful to be able to inspect the current log file for a service plus the archived log file immediately prior to the current one. Doing this with oxlog is presently somewhat difficult, because archived log files may exist across multiple datasets, and piping oxlog into sort(1) will not output the log files in chronological order, since they are sorted by the UUID of the dataset before sorting chronologically. This is unfortunate.

It would be nice if oxlog logs --archived had a way to select the N most recent archived logs. That way, a user who wishes to use grep or looker to search for an event in the current and most-recent-archived log files could run something like:

$ oxlog logs <SVC> --current --last 1 | xargs -L 1 cat | looker

or whatever.

Start at the oxlog logs command and run the existing archived-log listing behavior to understand how datasets and timestamps are presented. Add a way to select the N most recent archived logs in chronological order, then verify that the resulting paths support the stated grep or looker workflow.