In some cases if the transport drops out from underneath unixd,
it can be difficult to diagnose and leads to inconsistent errors
and output such as prompting for a password multiple times when
it can't succeed.
This makes it clearer that the transport had an error, and it
denies the inflight authsession to prevent spurious password
prompts.
Allow caching and checking of shadow entries (passwords)
Cache and serve system id's
improve some security warnings
prepare for multi-resolver
Allow the kanidm provider to be not configured
Allow group extension
This starts the support for multi-resolver operation as well as a system level nss resolver.
In future we'll add the remaining support to auth system users with pam too.