There isn't a hook which does individual project file inserts or deletes. For 12.0.1 (first patch), you could write a "_prjupdate_<your name>" function and it will get called when files are added or removed from the project by any means. You just won't know what files were added or removed. You'll need to fetch the list of files in the workspace or project to see if any changes actually happened. This won't work in 12.0. We enhanced this call back for 12.0.1 because we needed it for the new Files tool window.
Hope this helps you