delete by --older-than flag

Is your feature request related to a problem? Please describe. User should be able to delete node_modules that have not been accessed for over X days. The reason for this I usually have old projects/experiments I abandon and they're just taking up space for no reason.

Describe the solution you'd like Add a --older-than {X days} flag. I was inspired by (killpy)[https://github.com/Tlaloc-Es/killpy]

Describe alternatives you've considered I'll run a script to filter folders that have not been accessed for X days, then I'll call npkill on each one.