Suggestions for new PUDL data validations

[zaneselvans]

We've finally finished migrating all of our existing data validation tests into dbt. They're already more extensive than the old pytest + pandas setup, and also run in 45 seconds instead of 3 hours. With the new framework we can add many more validations without worrying about it blowing up our build times / resource usage. So... what should we be checking?

We're planning an internal hackathon to add a bunch of new validations later in the summer. If you're a PUDL user and have suggestions for new types of data validations you'd like to see applied to our outputs, please drop them in the comments here!