fw-engprod-tools: expand OWNERS

BUG=None
TEST=None

Change-Id: I40f59670b1f3ba18279130406399801d6d80ac47
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crostestutils/+/2090193
Tested-by: Kevin Shelton <kmshelton@chromium.org>
Auto-Submit: Kevin Shelton <kmshelton@chromium.org>
Commit-Queue: Greg Edelston <gredelston@google.com>
Reviewed-by: Greg Edelston <gredelston@google.com>