Write the difference between runApp() and main() in flutter.
In Flutter, `runApp()` and `main()` are both important methods used in the initialization and running of a Flutter application, but they serve different purposes.
`main()` : is the entry point of a Flutter app, just like in any other Dart application. It is a required method that starts the application and runs the code that initializes and sets up the app's environment. This includes setting up any global variables, importing libraries, and configuring the app's theme and layout.
`runApp()` : is a method provided by the Flutter framework that takes a widget and makes it the root of the widget tree for the app. This method is typically called at the end of the `main()` method, after all the app's dependencies and configurations have been set up.
