Add the --one-file-system flag

[ericcornelissen]

Feature Request

Summary

Add a flag similar to the rm(1) --one-file-system flag. Per the rm(1) options documentation:

       --one-file-system
              when removing a hierarchy recursively, skip any directory
              that is on a file system different from that of the
              corresponding command line argument

This would help improve the safety of this implementation of rm. As of writing, it's to be decided if instead the default behavior should be to enable this flag and provide a flag to disable this behavior.