Flutter notification
1, Create a firebase project 2, Setup & import the google-services.json file (nếu config n flavor => add n app, file json) 3, Add new lib in Gradle (step by step in firebase) 4, Show noti: https://blog.logrocket.com/implementing-local-notifications-in-flutter/#:~:text=Displaying%20a%20notification%20in%20Flutter,of%20notifications%20in%20Android%20devices. (Chỉ nên làm theo ảnh dưới nếu config 1 môi trường)