title: Get other user jti for flask-jwt-extended
body: <p>How to get 'jti', not mine but by the "username" ?
  On registration/login jti for access and refresh were assigned to 'username'. 
  All instructions and docs note only how to get my own jti to logout with smth. like this code:</p>
  
  <pre class="lang-py prettyprint-override"><code>class UserLogoutRefresh(Resource):
      @jwt_refresh_token_required
      def post(self):
          jti = get_raw_jwt()['jti']
          try:
              revoked_token = RevokedTokenModel(jti = jti)
              revoked_token.add()
              return {'message': 'Refresh token has been revoked'},200
          except:
              return {'message': 'Something went wrong'}, 500
  </code></pre>
  
  <p>How to get jti for another user.
  I suppose smth like:</p>
  
  <pre class="lang-py prettyprint-override"><code>jti = get_raw_jwt(identity='someusername')['jti']
  </code></pre>
  
  <p>has to exist for this, who knows ???</p>