In this PR, i have

• Change to use maven, with all of needed dependencies, can build to jar file and execute with command: mvn package
• Separate the logic of handling each button action in MusicPlayerView (old name is MusicPlayerGUI) to MusicPlayerController (old name is MusicPlayer)
• Create a constants package: store the Resoures path references to the src/main/resources directory
• Create a styles package: store color and frame size
• Create a models package: move class Song to there and using lombok

Thanks