(#10289) Add an ext script to upload facts to inventory server

This script, ext/upload_facts, will read facts from the master's yaml
dir and save them to the facts terminus. The intended use of this is
when the facts terminus is set to inventory_service, to be run
periodically via cron to ensure facts are uploaded even if the
inventory_service becomes temporarily unavailable. It supports a
--minutes option, which will limit the facts uploaded to only those
added in the last n minutes.