Comment 3 for bug 1902379

I disagree here:
when being started Mixxx should not make any sound on its own!
That's why we mute all mics and aux on startup that might still be attached to an active audio source.
For regular users engaging AutoDJ is no big deal.

For this special case here a command line option is more appropriate.
Also we finally need to add an Auto status light to all skins.