Add unique_key to stg_nodes, and/or full node config JSON

[ttusing]

Describe the feature

I'd like to write tests about the consistency or presence of unique_key in my incremental models, i.e., that is also the tested primary key, or that it is always present. I don't think these tests necessarily make sense for DBT project evaluator, but I was a bit surprised that they were not available.

Describe alternatives you've considered

Forking the repo and adding it.

Who will this benefit?

Power users of DBT Project Evaluator who write their own tests and want node config information.

Are you interested in contributing this feature?

Yep