pkgbase: Put ufs related tools and lib in their own package

It's not really useful in a jail or in a mdroot or even if a users
wants to do a full zfs machine.

Reviewed by: mckusick
Differential Revision: https://reviews.freebsd.org/D36227

(cherry picked from commit a7ffc948497e04354fa512915f7e383ee04ae269)