"Invert #if" refactoring

[jnm2]

This would be very similar to "Invert if," but it would be available for code like the following:

#if !NET3_0_OR_GREATER
            // Distribution is expected to be heavily weighted towards large palettes
            if (paletteLength > 128) return 8;
            if (paletteLength > 64) return 7;
            if (paletteLength > 32) return 6;
            if (paletteLength > 16) return 5;
            if (paletteLength > 8) return 4;
            if (paletteLength > 4) return 3;
            if (paletteLength > 2) return 2;
            return 1;
#else
            return paletteLength <= 2 ? (byte)1 :
                (byte)((sizeof(uint) * 8) - System.Numerics.BitOperations.LeadingZeroCount(paletteLength - 1));
#endif

Expected result:

#if NET3_0_OR_GREATER
            return paletteLength <= 2 ? (byte)1 :
                (byte)((sizeof(uint) * 8) - System.Numerics.BitOperations.LeadingZeroCount(paletteLength - 1));
#else
            // Distribution is expected to be heavily weighted towards large palettes
            if (paletteLength > 128) return 8;
            if (paletteLength > 64) return 7;
            if (paletteLength > 32) return 6;
            if (paletteLength > 16) return 5;
            if (paletteLength > 8) return 4;
            if (paletteLength > 4) return 3;
            if (paletteLength > 2) return 2;
            return 1;
#endif