Fix metadata / data provenance tracking

[g-k]

refs: #11

Currently, we set a __pytest_meta value in client.py get_aws_resource and propagate it in extract_key

Downsides:

• doesn't work for primitive values
• wastes memory and CPU propagating stuff to all items
• pollutes the data values the client uses

[g-k]

A giant dict, DB, or Pandas dataframes could work.