Start using cuddle for roundtrip testing

[lehins]

Currently we use a cddl tool written in Ruby that generates random data according to the cddl spec for us.

We want to start using cuddle to improve our testing

It should be setup in a similar fashion, except the cddl configuration will not be coming from a cddl file, but from the huddle specification defined in #4125

The goal is not to replace the ruby tool, but to improve out testing coverage.

[nc6]

This was addressed in #4437, at least going by the "start" keyword. Other eras will come under #4462