Remove need to loop speaker

[philipbl]

I removed the loop_speaker function and instead create a task that calls loop on the users behalf when playing notes in the background.

[philipbl]

@jgoeders, I would like to get your thoughts on the code. I think the changes I made here should work just fine in the y-board-v3 library because all the changes are done in the yboard.cpp file and not yaudio.cpp.

[philipbl]

Specifically, I want your thoughts on creating and then deleting the task if all the notes are done. My other thought was to create the task in the setup function and just let it sit there if there is nothing to play. But I liked the idea of not having the task running unless someone is using the speaker. 🤷

[jgoeders]

Looks pretty clean. If it works reliably, I think this is a good way to do it.

[philipbl]

Before we merge this, I would like to make sure removing loop_speaker from the v3 library (y-board/y-board-v3#25) is possible. I don't want the two APIs to get out of sync for too long.

[jgoeders]

@philipbl This looks great. Thanks for doing all this!