Handle expired interactions gracefully

[mkurapov]

Context

• After looking through the test wallet issue [BUG] Internal server error when taking too long to accept/decline grant testnet#1917, we noticed that we can handle the interaction expiry error better in the auth service
• First, we need to return proper errors in the interaction routes, such that the IDP can know why the interaction choice call failed (like expiry). This is being done in feat(auth): use gnap error middleware on idp api #3094.
• Second, in the finish route handler, instead of checking the session nonce first, we should check that the interaction has expired. If it has, we should redirect back to the client redirect URI with result=interaction_expired query param. If not expired, we should then check the session nonce.
• In general, other than the invalid session error, we should always redirect back to the client with the corresponding query param in the URL.

Todos

• feat(auth): use gnap error middleware on idp api #3094 is completed
• Check interaction expiry before session token in finish route
• Make sure to always redirect to client with a query param in finish route on errors (other than the invalid session error)