Integrate tools/regression/acltools into the FreeBSD test suite as tests/sys/acl

Integrate tools/regression/acltools into the FreeBSD test suite as tests/sys/acl

- Make the requirements more complete for the testcases
- Detect prerequisites so the tests won't fail (zfs.ko is loaded, zpool(1)
  is available, ACL support is enabled with UFS, etc).
- Work with temporary files/directories/mountpoints that work with atf/kyua
- Limit the testcases to work on temporary filesystems to reduce tainting the
  test host

MFC after: 2 weeks
Reviewed by: trasz (earlier version)
Differential Revision: https://reviews.freebsd.org/D3810