Support command output for denon receivers

For if you use the donon action (formerly service) denonavr.get_command you can’t get the actual command output:

But having that would be super useful, as otherwise you can’t query the state of LFC via PSLFC ?.

I’m currently implementing a custom button for LFC, because none is included already, but I can’t really update the state of that button as I have no way of getting the current state of LFC as you also can’t watch some with via telnet or so.

Integration: Denon AVR Network Receivers - Home Assistant