[Core] Add support for pseudocolumns in unit tests

### Link to the page(s) on docs.getdbt.com requiring updates

https://docs.getdbt.com/docs/build/unit-tests

### Tell us more about this update

https://github.com/dbt-labs/dbt-adapters/pull/1526

### Reviewers/Stakeholders/SMEs

@colin-rogers-dbt 

### Related GitHub issues

https://github.com/dbt-labs/dbt-adapters/issues/1517

### Additional information

_No response_