Training page statistics: Impact/Community & Maintainer Pages

Next step for this: https://github.com/galaxyproject/training-material/pull/4984
1) [Impact] Would be good to get a better description of 'Goal conversions' as idk what that means and I might use it more if I did. Like I think that's the 'I completed the tutorial' button probably? And then maybe that could be broken down across tutorials, and/or compared with "People accessing page vs Completing tutorial"

2) [Impact] Total tutorials over time (i.e. pull data from 'Date created' and then that can show a nifty graph)

3) [Impact] Contributors over time for the page (same concept?)

4) [Maintaining] So once Workflow testing is there, would also be good to have a 'Last updated' listing for each tutorial, and more specifically it can be organised

5) [Maintaining] We can't sort the listings, i.e. "Top pages" is awesome but I'd like to know the tutorials nobody is accessing (I.e. worst pages), as it might be we need to remove them as they are now antiquated.

6) [Maintaining] Incidentally, I can't actually download the data from the various lists as a table. Can a button be added to allow this?

Start with the training statistics work referenced in pull request 4984 and review the existing Impact and Maintaining pages. Compare the current lists and charts with the six requested capabilities: clearer goal conversions, time-based totals, contributor history, last-updated sorting, reverse page ranking, and downloadable tables; done means each agreed capability is available and usable.

Written by the indexing model from the issue text.