Make sure R packages leveraged using :: notation are included in reproducibility table

[kelliemac]

Currently R packages leveraged using :: notation are NOT included in the reproducibility table - only packages loaded with library() calls are included. We need to fix this.

Maybe we can leverage functionality from renv to scrape relevant files for :: usage?

This is mentioned in discussion on #35, but I'm making a separate issue for it because it's a spinoff from the original issue which is about using full renv functionality.