[Samba] winbind idmap customization

[Jerome Haltom]

I would like to have winbind map all of my AD users to their full
user at REALM form on the Linux domain members. I'd like lookups to be
properly canonical. Is this possible?

'getent passwd user' should return:
user at REALM.NET:*:1786588783:1786588745:Mr Man:/home/whatever:/bin/bash

I'm finding my options are to either have the local names be plain,
unprefixed, or prefixed, but without the ability to do canonical
mappings. It can either be `user` or `DOM\user`. But if it's DOM\user,
lookups for 'user' don't work properly.