pkgbase: Put yellow pages programs to its own package

YP is less and less used, split them to users have the choice to not
install them.

MFC after: 2 weeks
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D33441

(cherry picked from commit 5abb10faa1ff471b45ac4f49ace2b79cc57d7c3c)