Allow disabling blank liveries#1863

There should be an option to disable the injection of aircraft with blank liveries when BeyondATC cannot find a suitable matching livery.

Users should not be expected to install both the FSLTL and AIG aircraft models just to maximize livery coverage. Even when both packages are installed, aircraft still regularly appear at airports without a proper livery.

An option to simply skip the injection of an aircraft when no suitable livery is available would provide a much more realistic airport environment and improve immersion, especially at busy airports.