Provide a basic account system with login and server side session store
identified by a cookie. Upon successful login a signed session cookie
is set by the server with the session stored on the server identifying
which account it is logged in as. The client uses a shared useFetch on
the session endpoint to identify if it's logged in and which account it
is logged in as, and refreshes this when loggin in or out.
Provide a convenient wrapper for setting SHA-256 HMAC signed cookies and
retreiving them with the signature validated. The secret key is
configured in the NUXT_COOKIE_SECRET_KEY environment variable.