fix(auth): state missing from the response

cf https://www.facebook.com/groups/openwhyd/posts/3612287192386147/?comment_id=3613057635642436&mibextid=uJjRxr
solution: auth0/express-openid-connect#145 (comment)
reference: https://auth0.github.io/express-openid-connect/interfaces/CookieConfigParams.html
example: https://github.com/auth0/express-openid-connect/blob/8ade66846a1f041591e267d2296b02df2604f1f4/test/appSession.tests.js#L310

app/lib/auth0/index.js

@@ -78,6 +78,11 @@ exports.Auth0Wrapper = class Auth0Wrapper {
       secret: this.env.AUTH0_SECRET,
       clientID: this.env.AUTH0_CLIENT_ID,
       issuerBaseURL: this.env.AUTH0_ISSUER_BASE_URL,
+      session: {
+        cookie: {
+          domain: new URL(urlPrefix).hostname,
+        },
+      },
     });
   }