Allow unauthenticated GraphQL access in frontend without forcing dynamic rendering

Currently `authLink` in https://github.com/con2/kompassi/blob/8675cc8ba4e38c45f946b98e7a2c3ebbed21b13d/frontend/src/apolloClient.ts#L11 forces dynamic rendering due to use of `getServerSession` which in turn calls `cookies` and `headers`.

It would be preferred that high volume pages showing only public information could be cached for some seconds. This means all user specific information on those pages needs to be retrieved client-side. This means at least the session (`getServerSession` -> `useSession`) but there may be other instances as well.