add 'refresh' to FontAwesomeNode, use in unit-rates, https://github.com/phetsims/unit-rates/issues/123, https://github.com/phetsims/scenery-phet/issues/269
add 'refresh' to FontAwesomeNode, use in unit-rates, https://github.com/phetsims/unit-rates/issues/123, https://github.com/phetsims/scenery-phet/issues/269

phetsims/sun,phetsims/sun,phetsims/sun