spk ls -t to sort by time

[dcookspi]

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

Sometimes users want to list the versions or builds by time to see which ones were published first (or last). It would be good to have a way to sort ls output by time, or reverse time.

Describe the solution you'd like

Add a -t flag to spk ls to sort by time, either from a field in the package's metada or the time from tag file on disk.

For example, if you had a situation where python versions had been published in this order: 3.9.7, 3.10.10, and 3.10.8, then spk ls -t python would output:

> spk ls -t python
3.9.7
3.10.10
3.10.8