title: Getting the UserAuth from a ServiceStack Session
body: <p>During a basic or credentials authorization event, is there any place to get a handle on the UserAuth of the user being logged in in OnAuthenticated()?</p>
  
  <p>We've extended the AuthSession object and would like to populate it with more data from the UserAuth (including projecting some custom fields out of the Meta).</p>
  
  <p>I know we can load it ourselves by resolving the AuthRepo out of the authService, but I'm wondering if the current UserAuth is already available somewhere to keep us from spending those cycles needlessly.</p>