Update and create final solutions for the 'debug Node.js apps' course

[glaucia86]

In this PR contains:

• final solutions related with the Interactively debug Node.js apps with the built-in and Visual Studio Code debuggers course
• updating the files structure for this lesson

Some important changes for the lesson

In the exercise: Use the Node.js built-in debugger the file structure will be:

./nodejs-debug/4-exercise-built-debugger and the name of the file will be: fibonacci.js

In the exercise: Debug with Visual Studio Code the file structure will be:

./nodejs-debug/6-exercise-debug-with-vscode and the name of the file will be: currency.js

[diberry]

Thanks for adding the testing.