Accept non-privileged IQs from XEP-0356 privileged components.

mod_privilege current drops any non-privileged IQ received from a component
with an error about it not being properly wrapped. While this might
represent a mistake on the part of the component, it means that well-
behaved components can no longer send non-privileged IQs (something they
normally can do if mod_privilege isn't enabled).

Since mod_privilege is intended to grant additional permissions, and not
remove existing ones, route non-privileged IQs received from the component
normally, the same way we do with roster-query packets. The roster-query
and privilege-iq checks are both last in get_iq_encapsulated_details(), so
those checks don't bypass any other checks by short-circuiting; all we have
to do is not drop the packet.

src/mod_privilege.erl

@@ -309,7 +309,7 @@ component_send_packet({#iq{from = From,
                 drop;
             {_, {error, no_privileged_iq, _Err}} ->
                 ?INFO_MSG("IQ not forwarded: Component tried to send not wrapped IQ stanza.", []),
-                drop;
+                IQ;
             {_, {error, roster_query, _Err}} ->
                 IQ;
             {_, {error, ErrType, _Err}} ->