Abstract and subclass existing toolkit FileObject (for Licenses)

From parent feature:

Make abstract and then subclass the existing com.k_int.web.toolkit.files.FileObject into LOBFileObject and S3FileObject each with the same signature and a different implementation. 

Migration should add the default discriminator to the revised table structure to turn all FileObjects into LOBFileObjects.

upgrade script can then work through all LOBFileObjects converting them to S3FileObjects.

This will likely take time to complete at upgrade.

Since licenses don't have jobs (currently) it may be better manually triggered.

Existing LOB attachments should continue to work until all files are migrated.