Test type descriptions against Serde serialization

[randomPoison]

In order to test that generated Derive impls match the serialization logic generated by Serde, we'll need to setup a testing system that can compare the two directly. In order to do this, we can write a custom Serializer can take a Schema and an instance of the described type and compare the two while "serializing" the value in order to verify that the provided Schema accurately describes the resulting value.