feature: Add small widget

[danielepintore]

Hi, in this pull request I've added a widget like the one that is on the apple music app. The widget is simple it displays the song artwork, the song name and the artist name. There is a button that allows to start/stop the playback. Everything should be fine, but i think you should adjust the xcode project file with the correct developer account for the widget extension. Keep in mind that an app group should also be created. Here are some screenshots of the widget: