feat: Allow deserialization of StarkGenericConfigs

[preston-evans98]

This PR enables deserialization of the various StarkGenericConfig implementations. In the previous implementation, these types were serialized using the Serializer::serialize_none function, which was typically reserved for Option types. Now, these types are serialized as std::marker::PhantomData<Self> and deserialized by first deserializing a PhantomData instance and then dropping the Phantom and returning Self::new().

(Note: The Phantom deserialization is necessary for correctness, since serializers are allowed to serialize PhantomData into a non-empty byte sequence).