title: Custom icon for Fluent ui React northstar using svg
body: <p>I am using yarn  <a href="https://www.npmjs.com/package/@fluentui/react-northstar" rel="nofollow noreferrer">fluentui/react-northstar</a> and i need to add custom icon using  svg  as this <a href="https://fluentsite.z22.web.core.windows.net/0.53.0/icon-viewer" rel="nofollow noreferrer">https://fluentsite.z22.web.core.windows.net/0.53.0/icon-viewer</a>.</p>
  <p>is there proper way or guideline to do add custom icons?</p>