useTertiary property

Use effective FlexColorScheme.tertiary color as key generation input color for all ColorScheme secondary colors.

If set to false, the FlexColorScheme.primary will be used as key color input for secondaries as well, using same algorithm as in ColorScheme.fromSeed, thus the tertiary colors will be same as if we would have used it with the FlexColorScheme.primary color as input.

Defaults to false.