Complete the usr.bin/yacc kyua integration work I originally
submitted via r268811

- Install the Kyuafile by adding FILES to FILESGROUPS
- Run the testcases with an unprivileged user

  Some of the testcases depend upon behavior that's broken when
  run as root on FreeBSD because of how permissions are treated
  with access(2) vs eaccess(2), open(2), etc

- Simplify the test driver to just inspect the exit code from
  run_test because it now exits with 0 if successful and exits
  with !0 if unsuccessful
- Don't do ad hoc temporary directory creation/deletion; let Kyua
  handle that
- Add entries for files removed in r268811 to
  OptionalObsoleteFiles.inc

PR: 191020
X-MFC with: r268811
Approved by: jmmv (mentor)
Reviewed by: bapt
Sponsored by: EMC / Isilon Storage Division