pkgbase: Create a FreeBSD-utilities package and make it the default one

The default package use to be FreeBSD-runtime but it should only contain
binaries and libs enough to boot to single user and repair the system, it
is also very handy to have a package that can be tranform to a small mfsroot.
So create a new package named FreeBSD-utilities and make it the default one.
Also move a few binaries and lib into this package when it make sense.
Reviewed by: bapt, gjb
Differential Revision: https://reviews.freebsd.org/D21506