desktopToDarwinBundle: use ARGB format (#386434)

    }

    # macOS does not correctly display 16x and 32x png icons on app bundles

    # they need to be converted to rgb+mask (argb is supported only from macOS 11)

    # they need to be converted to argb

    function convertIfUnsupportedIcon() {

        local -r in=$1

        local -r iconSize=$2

        local -r scale=$3

        local -r out=${in%.png}.rgb

        local -r out=${in%.png}.argb

        if [[ ($scale -eq 1) && ($iconSize -eq 32 || $iconSize -eq 16) ]]; then

            echo "desktopToDarwinBundle: converting ${iconSize}x icon to rgb" >&2

            echo "desktopToDarwinBundle: converting ${iconSize}x icon to argb" >&2

            icnsutil convert "$out" "$in"

            rm "$in"

        fi