s4:kdc: Add device to default groups for RBCD conditions evaluation

s4:kdc: Add device to default groups for RBCD conditions evaluation

This means that expressions like ‘Device_Member_of(WD)’ will now work,
as they should.

It *also* means that expressions like ‘Device_Member_of(NU)’ will work,
even though they shouldn’t. This is because we consider SID_NT_NETWORK
to be a default group.

Our new behaviour may be wrong, but at least it’s now consistent with
the behaviour of user‐relative expressions like ‘Member_of(WD)’ and
‘Member_of(NU)’.

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>