pkgbase: Create a FreeBSD-ftp package

ftp tools aren't that useful nowadays but some might want them.
Create a FreeBSD-ftp package so users have a choice to have
them or not.

Differential Revision: https://reviews.freebsd.org/D31794

(cherry picked from commit b5be5c35dbaf38caaa9c70a83025f3535abbfd4f)