Hyperlink to Cognito login UI doesn't work when app is hosted on streamlit cloud.

[sammck]

Hi,

I've noticed that the LOGIN/LOGOUT buttons do not work when the app is hosted on streamlit cloud. This is because the app is put into an IFRAME, so the navigation only applies to the iframe, and Cognito does not allow login/logout within an IFRAME. I don't think there is any pretty way to work around this until streamlit provides an API for navigating the top-level window.

In my own fork, I dealt with this as a special case when the APP_URI is on *.streamlitapp.com by using a standard streamlit button that when clicked simply prints an st.warning() that explains the problem and gives the login/logout URI that the user can manually copy/paste into their address bar to login or logout.

If you add an open source license (MIT preferred), I'd be happy to provide a pull request if you're interested...