bsdinstall/scripts/hardening: replace dialog with bsddialog (and fix --separate-output).

[asiciliano]

Summary

Replace dialog with bsddialog in bsdinstall/scripts/hardening, fix bsddialog --separate-output,
add a "retval check" to avoid to do anything with ESC key and bsddialog error.

Test Plan

Menu, radiolist, checklist and mixedlist are the most tested features of bsddialog (tzsetup, kbdmap, portconfig).