[VSCode] Start Debugging from any entrypoints.

launch.json

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Flutter",
            "request": "launch",
            "type": "dart",
            //現在開いているファイルから実行する run by current open file
            //"program": "${file}",
            //lib/main.dartkから実行する(defaultと同じ) run by lib/main.dartk. as default setting.
            "program": "${workspaceFolder}/lib/main.dart",
        }
    ]
}