Indicate on the BeyondATC window when the radio volume is set to zero#1690

Some aircraft initialize with the COM1 volume set to 0. Now that BeyondATC uses the COM1 volume (a great addition), I have, on more than one occasion, thought BeyondATC’s voices weren’t working when in fact it was just that I needed to turn the volume up. It would be nice if some indication on the window showed that the radio was muted.