Data class with model validation

Implement/use a data class library to improve how to serialize/deserialize data while communicating with CloudFormation, and, the same time, validate the model. A library like [TypedJSON](https://github.com/JohnWeisz/TypedJSON) should be easy to adopt without increasing too much the bundled size.

Start by reviewing the TypeScript plugin's generated data-model and CloudFormation communication paths, then evaluate the linked TypedJSON library for serialization, deserialization, and model validation. Done means adopting an approach that provides those capabilities without significantly increasing the bundled size.

Written by the indexing model from the issue text.