zv: add SerializeValue/DeserializeValue

Those helpers will help to serialize/deserialize to known and complex Value types, without having to wrap them to the dynamic Value type.

Change SerializeDict and DeserializeDict to make use of it. Now, those macros work seamlessly with any field of T: Type+Serialize+Deserialize.

This will help fixing #80 (closed) (where the value.try_into::<Vec<f64>>() or value.try_into::<[f64;3]>() was failing)