Federated Server: Unify remote table listing

- Removes DB_Federated_Server_List_Registered_Tables in favor
of CDB_Federated_Server_List_Remote_Tables that now returns
both registered and unregistered tables and, when they are
registered, the information about the associated view

test/CDB_FederatedServerListRemote.sql

@@ -4,7 +4,6 @@
 \set QUIET on
 SET client_min_messages TO error;
 \set VERBOSITY terse
-SET SESSION AUTHORIZATION postgres;
 CREATE EXTENSION postgres_fdw;
 
 CREATE ROLE cdb_fs_tester LOGIN PASSWORD 'cdb_fs_passwd';