R1:fe5cd4ca2c77

Move FontIcon calls to Icon

Summary: Normalizes all `setFontIcon` calls to `setIcon`.

Test Plan: UIExamples, Almanac, Apps list, etc.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, hach-que, yelirekim

Differential Revision: https://secure.phabricator.com/D15129