keygeneration: add some output helpers

These use the same forms as in other shell projects in CrOS.

BUG=b:35587169
TEST=ran create_new_android_keys.sh and new output works
BRANCH=None

Change-Id: Id75fd77203795d7837537f12ab948376a7ad105e
Reviewed-on: https://chromium-review.googlesource.com/520786
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>
4 files changed