Nextjs Firebase-v9-cloud-messaging

In firebase, You have to generate

1. Generate VapidKey and applied in file "./firebase/firebase.js"
2. You have to add config variables. "./firebase/firebase.js" and "./public/firebase-messaging-sw.js"
3. After, you execute de npm run dev. It will appear the token in the console, you can use that token to send a test message. and it will send the foreground and background notification.