More descriptive history entries for Blank Model Changes

Model history can contain entries saying "Blank Model Change", which can occur for example when changing the SSO access of a user. These could be more informative so we can understand what the change was.

Another example - if you are setting a users access, it is usual to copy another users access by selecting an entire row, and pasting it into the user you are giving access. If you have many lists in the model which have selective access, you will end up with a Blank Model Change for each cell you pasted blank into. These should be more descriptive history entries to avoid confusion and/or concern when reviewing the history of changes.