Summary: Ref T8755, Adds full fallback support for Lato, the default Phabricator font and champion of Azeroth.
Test Plan: Verify fonts are being used everywhere as expected.
Reviewers: btrahan, epriestley
Reviewed By: epriestley
Subscribers: epriestley, Korvin
Maniphest Tasks: T8755
Differential Revision: https://secure.phabricator.com/D13553
