[TIMOB-18860] Windows: Introduce Nullable templated type in TitaniumKit APIs

We have no notion of "null" primitive values. This is problematic when we have special arguments/parameter structs like MatrixCreationDict. It's also problematic if we want to check if a property has never been assigned a value (say color, on an animation). We can use "default" values and check for those (such as empty string), but for double/int32_t, uint32_t that's often more problematic. We want to explicitly know if the user gave a 0/-1/whatever versus never having set a value. There's the boost:optional type we could use, or we could simply make our own type.