Procedurally add 'Additional non-asset directories to copy'

The context is a plugin with a custom asset type. The asset is dependent on some raw resource files that should be copied on deployment. I’d like to know if there is somewhere I can hook into the packaging process (without modifying the engine) so that I can update this list of additional directories to copy for each asset that gets cooked?

Currently I am just updating the list on asset import/deletion, which is not so robust and also results in files being deployed for assets which may not be referenced and therefore don’t themselves end up being packaged.

bump this too