Add missing invocations to object access hooks

The following commands have been missing calls to object access hooks
InvokeObjectPost{Create|Alter}Hook normally applied to all commands:
- ALTER RULE RENAME TO
- ALTER USER MAPPING
- CREATE ACCESS METHOD
- CREATE STATISTICS

Thanks also to Robert Haas for the discussion.

Author: Mark Dilger
Reviewed-by: Álvaro Herrera, Michael Paquier
Discussion: https://postgr.es/m/435CD295-F409-44E0-91EC-DF32C7AFCD76@enterprisedb.com

src/backend/commands/foreigncmds.c

@@ -1343,6 +1343,9 @@ AlterUserMapping(AlterUserMappingStmt *stmt)
 
 	CatalogTupleUpdate(rel, &tp->t_self, tp);
 
+	InvokeObjectPostAlterHook(UserMappingRelationId,
+							  umId, 0);
+
 	ObjectAddressSet(address, UserMappingRelationId, umId);
 
 	heap_freetuple(tp);