macos: add script to notarize OpenAFS

macos: add script to notarize OpenAFS

In order to integrate the notarization process into our existing build
scripts, this patch introduces a script to automatically notarize the
OpenAFS package.

Reviewed-on: https://gerrit.openafs.org/13671
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Cheyenne Wills <cwills@sinenomine.net>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 0563642cc1cb750c69a6471005adf36fabb2b7e3)

Change-Id: I50265b3305eb12db45371da1bf1982a6722c0018
Reviewed-on: https://gerrit.openafs.org/14036
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Cheyenne Wills <cwills@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>