Add a 'link status' filter to the digitisations 'Requests report'

Currently, if a list or list item is deleted which had a digitisation linked to it, the digitisation remains Live in the system.

In these cases, when you click the link "View item in reading list" within the Live digitisation, you are taken to an error screen.

It would be extremely useful if there was an alert or indication of some kind when the link between the digitisation and list item/list has broken, so librarians can follow up.

Furthermore, if the digitisation had no student interactions, it would be really clever if the system could automatically withdraw the digitisation.

Also there is currently no quick way to tell if/ which live digitisations have not ever been linked to any reading list item.

To address these issues, please add a 'link status' filter to the Request report, so requests can be found that have broken links to reading lists/list items, or no link to a reading list/list item.