Rework internals of changing a type's ownership

This is necessary so that REASSIGN OWNED does the right thing with
composite types, to wit, that it also alters ownership of the type's
pg_class entry -- previously, the pg_class entry remained owned by the
original user, which caused later other failures such as the new owner's
inability to use ALTER TYPE to rename an attribute of the affected
composite.  Also, if the original owner is later dropped, the pg_class
entry becomes owned by a non-existant user which is bogus.

To fix, create a new routine AlterTypeOwner_oid which knows whether to
pass the request to ATExecChangeOwner or deal with it directly, and use
that in shdepReassignOwner rather than calling AlterTypeOwnerInternal
directly.  AlterTypeOwnerInternal is now simpler in that it only
modifies the pg_type entry and recurses to handle a possible array type;
higher-level tasks are handled by either AlterTypeOwner directly or
AlterTypeOwner_oid.

I took the opportunity to add a few more objects to the test rig for
REASSIGN OWNED, so that more cases are exercised.  Additional ones could
be added for superuser-only-ownable objects (such as FDWs and event
triggers) but I didn't want to push my luck by adding a new superuser to
the tests on a backpatchable bug fix.

Per bug #13666 reported by Chris Pacejo.

Backpatch to 9.5.

(I would back-patch this all the way back, except that it doesn't apply
cleanly in 9.4 and earlier because 59367fdf9 wasn't backpatched.  If we
decide that we need this in earlier branches too, we should backpatch
both.)

src/test/regress/expected/dependency.out

@@ -84,13 +84,31 @@ DROP OWNED BY regression_user1;
 \d deptest
 -- Test REASSIGN OWNED
 GRANT ALL ON deptest1 TO regression_user1;
+GRANT CREATE ON DATABASE regression TO regression_user1;
 SET SESSION AUTHORIZATION regression_user1;
+CREATE SCHEMA deptest;
 CREATE TABLE deptest (a serial primary key, b text);
+ALTER DEFAULT PRIVILEGES FOR ROLE regression_user1 IN SCHEMA deptest
+  GRANT ALL ON TABLES TO regression_user2;
+CREATE FUNCTION deptest_func() RETURNS void LANGUAGE plpgsql
+  AS $$ BEGIN END; $$;
+CREATE TYPE deptest_enum AS ENUM ('red');
+CREATE TYPE deptest_range AS RANGE (SUBTYPE = int4);
 CREATE TABLE deptest2 (f1 int);
 -- make a serial column the hard way
 CREATE SEQUENCE ss1;
 ALTER TABLE deptest2 ALTER f1 SET DEFAULT nextval('ss1');
 ALTER SEQUENCE ss1 OWNED BY deptest2.f1;
+-- When reassigning ownership of a composite type, its pg_class entry
+-- should match
+CREATE TYPE deptest_t AS (a int);
+SELECT typowner = relowner
+FROM pg_type JOIN pg_class c ON typrelid = c.oid WHERE typname = 'deptest_t';
+ ?column? 
+----------
+ t
+(1 row)
+
 RESET SESSION AUTHORIZATION;
 REASSIGN OWNED BY regression_user1 TO regression_user2;
 \dt deptest
@@ -100,10 +118,19 @@ REASSIGN OWNED BY regression_user1 TO regression_user2;
  public | deptest | table | regression_user2
 (1 row)
 
+SELECT typowner = relowner
+FROM pg_type JOIN pg_class c ON typrelid = c.oid WHERE typname = 'deptest_t';
+ ?column? 
+----------
+ t
+(1 row)
+
 -- doesn't work: grant still exists
 DROP USER regression_user1;
 ERROR:  role "regression_user1" cannot be dropped because some objects depend on it
-DETAIL:  privileges for table deptest1
+DETAIL:  owner of default privileges on new relations belonging to role regression_user1 in schema deptest
+privileges for database regression
+privileges for table deptest1
 DROP OWNED BY regression_user1;
 DROP USER regression_user1;
 \set VERBOSITY terse

src/test/regress/sql/dependency.sql

@@ -74,20 +74,37 @@ DROP OWNED BY regression_user1;
 
 -- Test REASSIGN OWNED
 GRANT ALL ON deptest1 TO regression_user1;
+GRANT CREATE ON DATABASE regression TO regression_user1;
 
 SET SESSION AUTHORIZATION regression_user1;
+CREATE SCHEMA deptest;
 CREATE TABLE deptest (a serial primary key, b text);
+ALTER DEFAULT PRIVILEGES FOR ROLE regression_user1 IN SCHEMA deptest
+  GRANT ALL ON TABLES TO regression_user2;
+CREATE FUNCTION deptest_func() RETURNS void LANGUAGE plpgsql
+  AS $$ BEGIN END; $$;
+CREATE TYPE deptest_enum AS ENUM ('red');
+CREATE TYPE deptest_range AS RANGE (SUBTYPE = int4);
 
 CREATE TABLE deptest2 (f1 int);
 -- make a serial column the hard way
 CREATE SEQUENCE ss1;
 ALTER TABLE deptest2 ALTER f1 SET DEFAULT nextval('ss1');
 ALTER SEQUENCE ss1 OWNED BY deptest2.f1;
-RESET SESSION AUTHORIZATION;
 
+-- When reassigning ownership of a composite type, its pg_class entry
+-- should match
+CREATE TYPE deptest_t AS (a int);
+SELECT typowner = relowner
+FROM pg_type JOIN pg_class c ON typrelid = c.oid WHERE typname = 'deptest_t';
+
+RESET SESSION AUTHORIZATION;
 REASSIGN OWNED BY regression_user1 TO regression_user2;
 \dt deptest
 
+SELECT typowner = relowner
+FROM pg_type JOIN pg_class c ON typrelid = c.oid WHERE typname = 'deptest_t';
+
 -- doesn't work: grant still exists
 DROP USER regression_user1;
 DROP OWNED BY regression_user1;