Add a "ledger" to track which resources a study was run against

[mikix]

Problem Statement
A "ledger" of which resources are being examined by a given study (a record of resources & their ids) would be useful for a few reasons:

• You could feed an export of that ledger to data-metrics and have it only analyze the given resources (feature does not yet exist in data-metrics)
• You could re-run a study on the same historical data as a previous run of a study (would need further work in the Library to do this)
• If investigating something down the line, you could look back and see what exactly the study was working off of

Desired behavior
I don't want to be too prescriptive over how this would work. But I'd imagine if we could store the following for any given study run:

• timestamp
• a mapping of resource & id for every included/examined resource

And then if that's the sort of artifact that you could download/export from athena into a csv, that would be cool.