[Experimental simulators] Improve serialization of noise models in C#

[cgranade]

Please describe what you would like the feature to accomplish.
Currently in #714, states and processes in noise models are represented by a discriminated union in Rust, which is then serialized to JSON using serde before sending to C# code. It would be nice to have a more automated way to treat serialization and deserialization of these Rust DUs in C# to reduce the amount of custom converter logic that needs to be written for each DU. This would reduce the code volume and make it easier to extend noise models to include new variants in future iterations.