Implement bot-challenge-page to throttle bot requests

[srappel]

Use the rack-attack gem to throttle requests.

https://github.com/rack/rack-attack

Most discussion of this tool was from 2020 or earlier, so I'm not sure if it's a cure for the bot attacks but maybe it will slow things down.

[srappel]

Some work on this was done here: #265

Still some work in progress here: #269