Package code for harvesting digitised collections from Trove

The [code that I've been using recently](https://wragge.github.io/trove-data-guide/other-digitised-resources/how-to/harvest-digitised-resources.html) for harvesting digitised collections (other than newspapers) is probably getting to the point where it could be packaged up. There are some variations by format, but I think these could be handled?