Add an option to modify the pitch tone of a song

Hi everyone !

Today, it's my first suggest to help to make AzuraCast more complete with a few new options like this one who allows to modify the pitch tone of a song (= "Change Speed" option in Audacity). There are many reasons to add this feature :
- Play more songs in a same amount of time
- It allows to some stations to have modified musics which more to their style, give some dynamism (Ex: Electro, Rap, Hits)

You can listen the difference with and without here :
WITH : https://mega.nz/file/cl4llIoI#gFCpoZtEblMUgx0DQNReYm4b28QbwLsujXdkHWH_8s8
WITHOUT : https://mega.nz/file/w1oxDSBA#_vkU30CkFfrj5Sb_sK_DAJ9tPCrHZnWRYgrnJC2eoHY

To implement this feature, I suggest to add an option to modify the pitch tone of a playlist or / and a song.

Thanks for all the work you do for AzuraCast !