Add visualization_color to LuaFluidPrototype (runtime)

[asher_sky]

It would be handy to have the FluidPrototype visualization_color property readable at runtime from LuaFluidPrototype.
It's not so hard to just calculate it in control, but if a mod defines a custom value it seems there's no way to know what it is.

[Bilka]

Thanks for pointing this out, added for 2.0.77.