Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

zfs: multiple improvements to the zpool_add tests

* Don't partition a disk if too few are available. Just rely on Kyua to
ensure that the tests aren't run with insufficient disks.

* Remove redundant cleanup steps

* In zpool_add_003_pos, store the temporary file in $PWD so Kyua will
automatically clean it up.

* Update zpool_add_005_pos to use dumpon instead of dumpadm. This test had
never been ported to FreeBSD.

* In zpool_add_005_pos, don't format the dump disk with UFS. That was
pointless.

MFC after: 2 weeks
Sponsored by: Axcient

ZFS: fix the zpool_add_010_pos test

The test is necessarily racy, because it depends on being able to complete a
"zpool add" before a previous resilver finishes. But it was racier than it
needed to be. Move the first "zpool add" to before the resilver starts.

MFC after: 2 weeks
Sponsored by: Axcient

Add the ZFS test suite

It was originally written by Sun as part of the STF (Solaris test framework).
They open sourced it in OpenSolaris, then HighCloud partially ported it to
FreeBSD, and Spectra Logic finished the port. We also added many testcases,
fixed many broken ones, and converted them all to the ATF framework. We've had
help along the way from avg, araujo, smh, and brd.

By default most of the tests are disabled. Set the disks Kyua variable to
enable them.

Submitted by: asomers, will, justing, ken, brd, avg, araujo, smh
Sponsored by: Spectra Logic Corp, HighCloud