Redirect to desired page after login

In #1318 we addressed an error that was being thrown when an unauthenticated user attempted to access a route that required auth. This kind of thing can happen when:

1. a user clicks a link that friend shared, it opens a new browser tab for a protected resource, the user hasn't logged into openfn for N days, the user gets redirected to login
2. a user leaves their browser open for a day on the history page, their session expries, and they then click into an attempt on that page, they get redirected to login

In both of these cases, after they re-authenticate, we want to redirect the user to the page that they had originally tried to access.

Right now @midigofrank notes that:

• If the websocket connection dies within those 3 days, which is most likely, then it means when the user comes back, they’ll be redirected to login but with the correct return_path
• Assuming the websocket connection doesn’t die, if the user attempts to move to another page within the same live_session then we might have a problem

Start by tracing the login redirect and live_session behavior described in this issue, including the existing return_path handling from #1318. Done means that users redirected from protected resources return to the originally requested page after re-authentication, including the session-expiry cases described.