Define and document workflow output structure

[jashapiro]

Most workflow results, especially those that that may be used in downstream analyses, will be placed in the openscpca-nf-workflow-results bucket.

A current thought for the structure of that bucket is that there will be a set prefix for each release of the workflow, with subdirtectories for each module that all outputs from that module will include. For example, if there is a module named merged-sce, and an associated release of 2024-04-01, the outputs would be placed within:

s3://openscpca-nf-workflow-results/2024-04-01/merged-sce

Comments on this proposed structure are welcome in this issue before we start to implement it!

This structure should be implemented in at least one example module, and documentation about that implementation should be added to the README and/or contributing docs.