image_signing: sign UEFI binaries

BUG=b:62189155
TEST=See CL:*601769
BRANCH=none

Change-Id: Id9569616bae0d5f44c1c96e18522ace244a5aae8
Reviewed-on: https://chromium-review.googlesource.com/995175
Commit-Ready: Edward Jee <edjee@google.com>
Tested-by: Edward Jee <edjee@google.com>
Reviewed-by: Jason Clinton <jclinton@chromium.org>
5 files changed