Prototype use of foreign key wandb Tables for datasets

[charlesfrye]

1. Make a (smaller?) version of the dataset as a Table.
2. Use Foreign Keys to build train/test/val datasets as "references" to the original dataset.

First look into using "Foreign Keys" to reference the contents of one table inside another. Does this work across artifacts or only within artifacts? Ask Tim Sweeney and/or Stacey for help -- Tim should have a demonstration notebook/script. Try on a test setup/"hello world" example first to determine the workflow.

[charlesfrye]

Take notes on the Foreign Key process so that we can later reference them when writing docs/guides.