🚀 Add option in config to have a persistent queue

[sanslash332]

it would be awesome if you can activate for your server a persistent queue support.
With that, you can create a playlist for your server, and each time that you start your application, the bot has the same songs that had on the last session.

The solution can be a simple flag that you set in your config file that sets that you want to use a persistent queue, and the name of the file / small database where the song information will be saved.

So when you have the flag activated, each time a user adds a song into the queue, that song is added.

I just know one bot that does that, and is awesome; sadly it droped youtube support because is a public bot; not self-hosted.