* Added auto-generated uidNumber and guidNumber generated attributes for
use with SSSD and similar software.
The starting number for uid/gid can be configured iva environtment
variables and is by default 2000 which should work fine for most instances unless there are more than
999 local accounts on the server/computer.
The uidNumber is just the users Pk + the starting number.
The guidNumber is calculated by the last couple of bytes in the uuid of
the group + the starting number, this should have a low enough chance
for collisions that it's going to be fine for most use cases.
I have not added any interface stuff for configuring the environment variables as I couldn't really find my way around all the places I'd have to edit to add it and the default values should in my opinion be fine for 99% use cases.
* Add a 'fake' primary group for each user
* First attempt att adding config to interface
* Updated API to support new fields
* Refactor code, update documentation and remove obsolete comment
Simplify `GetRIDForGroup`, was a bit overcomplicated before.
Add an additional class/struct `LDAPGroup` which is the new argument
for `pi.GroupEntry` and util functions to create `LDAPGroup` from api.Group and api.User
Add proper support in the interface for changing gidNumber and uidNumber starting points
* make lint-fix for the migration files
