Add "Silent" option to double-kick menu so you can turn BGM on and off between songs

[jaredmorgs]

I remember in earlier versions of drummania you could change whether the background music played for a track from the ◀️ ▶️ menu.

The double-kick menu (the one that appears when you double-kick the bass pedal) could have this option available so you don't have to page through several menus to get to the feature.

I know playspeed and other settings on the SYSTEM and DRUM configuration menus are available in this menu, so it seems like it is possible?

Whether this is something worth investing time (and UI space) on is a question for the maintainers/community.