Add tab completion for ALTER FOREIGN TABLE ... SET

The schema is the only thing that can be set for foreign tables.

Author: ilmari

src/bin/psql/tab-complete.in.c

@@ -2447,6 +2447,10 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("ADD", "ALTER", "DISABLE TRIGGER", "DROP", "ENABLE",
 					  "INHERIT", "NO INHERIT", "OPTIONS", "OWNER TO",
 					  "RENAME", "SET", "VALIDATE CONSTRAINT");
+	else if (Matches("ALTER", "FOREIGN", "TABLE", MatchAny, "SET"))
+		COMPLETE_WITH("SCHEMA");
+	else if (Matches("ALTER", "FOREIGN", "TABLE", MatchAny, "SET", "SCHEMA"))
+		COMPLETE_WITH_QUERY(Query_for_list_of_schemas);
 
 	/* ALTER INDEX */
 	else if (Matches("ALTER", "INDEX"))