CE-2699: Error handling login and logout

So, this is a little bit different than other api errors since we handle login and logout with a redirect from backend and with a window.open. The error messages are hardcoded here to show you how it will look, but it will use error message that is coming from BE or browser. This is a bit of an edge case, but at least it is handled gracefully when it occurs.

Also removed setUser on logout since that is done automatically in the useEffect.