Pipeline enhancements - checks and documentation

- Add configurable checks to `airtable_to_bq` pipeline before merging prod and staging 
- Add `populate_column_documentation` to `airtable_to_bq` pipeline
- Add ability to exclude columns when in `bq_to_airtable` pipeline

These are features that would be useful in https://github.com/georgetown-cset/eto-st-newsfeed/pull/118