sudo expects the same name in sudo rule as login name. Therefore
if fully qualified name is used or even enforced by setting
use_fully_qualified_names to true or by forcing default domain
with default_domain_suffix sssd is able to correctly return the
rules but sudo can't match the user with contect of sudoUser
attribute since it is not qualified.

This patch changes the rules on the fly to avoid using names at all.
We do this in two steps:
1. We fetch all rules that match current user name, id or groups and
   replace sudoUser attribute with sudoUser: #uid.
2. We fetch complementry rules that contain netgroups since it is
   expected we don't have infromation about existing netgroups in
   cache, sudo still needs to evaluate it for us if needed.

This patch also remove test for sysdb_get_sudo_filter since it wasn't
sufficient anyway and I did not rewrite it since I don't thing it
is a good thing to have filter tests that depends on exact filter
order.

Resolves:
https://fedorahosted.org/sssd/ticket/2919

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>

The timestamp cache tests look into ldb to check the timestamps. This
patch converts the lookups to qualified names to make sure the lookups
actually match.

The conversion to sysdb made several functions obsolete. Remove them.

name.name is the input name. Since cache_req is an internal interface,
we need to return the sysdb name instead.

Creating the username part of the ccache file is an output operation, it
makes sense to use sss_output_name() there which parses the name out of
the internal qualified name.

The name is converted from whatever we receive on input to the internal
format before processing the data further.

Adds a utility function sized_output_name() which wraps the output_name()
function and returns the sized_struct structure. This function is used
when formatting the output name for the client, but also when
saving/deleting the memory cache entries.

Its sister function sized_member_name() is very similar, but infers the
domain name from memberuid or ghost attribute.

Because all names internally are used in the same format, the logic to
append domain or format the usename for output in the fill_XXX() family
of functions is much simpler. In general, adding a domain suffix no
longer relies in the domain being a subdomain, but only the dom->fqnames

The parse_member() function was removed because it is no longer
required.

The nss test was amended to store names in the internal fqdn format on
input and checks for either shortnames or qualified names with the right
format created using sss_tc_fqname() on output.

When storing users and groups by their name in the negative cache, store
them fully qualfied so that the responder only has to track the name in
the internal format once the input is converted.