This method is invoked when {@link TAuthManager::setAllowAutoLogin AllowAutoLogin} is set true.
The default implementation does nothing, meaning auth data is not stored in the cookie
(and thus automatic login is not supported.)
If you want to support automatic login (remember login), you should override this method.
Typically, you generate a unique token according to the current login information
and save it together with the username in the cookie's value.
You should avoid revealing the password in the generated token.
