[SSSD] fully qualified sysdb names for users and groups

[Jakub Hrozek]

Hi,

here is my branch that implements using the fully qualified names in sysdb
for users and groups:
    https://github.com/jhrozek/sssd/commits/sysdb-fqdn

The SSSD code changes are done. There are some downstream tests that are
failing (some sudo and some HBAC tests), but I think I can chase those
down quickly.

But -- I still don't have the upgrade code written and I only tested the
IPA overrides and IPA-AD trust code manually, so there might be a lot of
bugs there. It is also a lot of stuff to review.

With that in mind, I would like to ask other developers for opinions --
should we still pursue pushing this refactoring into 1.14? Or should we
release 1.14.0 first and push this patchset as the first thing into
1.15?

I'm really on the fence myself.