Audio-passthrough support for Chromecast

Like on Android, the iOS UI should expose sout-chromecast-audio-passthrough for the audiophiles.

changed milestone to %Future

added Interface Maintenance libvlc/Core + 1 deleted label

assigned to @fkuehne

changed milestone to %3.2.9

mentioned in merge request !172 (merged)

closed via merge request !172 (merged)