User filters not migrated when user only has builtin roles
The permissions migration added in #812 doesn't migrate user filters if they only have builtin roles associated.
0. Use pre-#812 Foreman
1. Create a user with no roles (they'll get the implicit Anonymous builtin role)
2. Edit the user and add a filter on a host group
3. Migrate to post-#812
4. Check the user, they'll have no roles but should've got a personalised one