pkgbase: Create a FreeBSD-telnet package

[manu]

Summary

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

[emaste]

Similar comment as another review, I wonder if we shouldn't drop telnetd entirely. But this makes sense for now.

[manu]

In D31791#717277, @emaste wrote:

Similar comment as another review, I wonder if we shouldn't drop telnetd entirely. But this makes sense for now.

Even without telnetd there will be too much bikesched if we want to remove telnet so I expect this package to be present for a long time :)