Add --no-audio support to VM spec (#460)

tart run supports --no-audio to disable host audio pass-through, but
there was no way to request it through a VM's spec - Headless, Nested,
and Suspendable all have a flag/field but audio didn't. Useful on
headless hosts with no audio hardware, where audio pass-through can
make guest CoreAudio depend on host audio services that don't exist.

internal/worker/vmmanager/tart/tart.go

@@ -303,6 +303,10 @@ func (vm *VM) run(ctx context.Context, eventStreamer *client.EventStreamer) {
 		runArgs = append(runArgs, "--nested")
 	}
 
+	if vm.resource.NoAudio {
+		runArgs = append(runArgs, "--no-audio")
+	}
+
 	if vm.resource.Suspendable {
 		runArgs = append(runArgs, "--suspendable")
 	}