R1:d2895249ee5e

Add Persona login icon

Summary: Adds the new icon 1x and 2x

Test Plan: photoshop

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Maniphest Tasks: T3958

Differential Revision: https://secure.phabricator.com/D7316