Support CTE with column labels

with cte1(a, b) as (select int_col x, bigint_col y from t1)
select a, b from cte1

a	b
1	2
3	4

<query expression> ::=
  [ <with clause> ] <query expression body>
  [ <order by clause> ] [ <result offset clause> ] [ <fetch first clause> ]

<with clause> ::=
  WITH [ RECURSIVE ] <with list>

<with list> ::=
  <with list element> [ { <comma> <with list element> }... ]

<with list element> ::=
  <query name> [ <left paren> <with column list> <right paren> ]
  AS <table subquery> [ <search or cycle clause> ]

<with column list> ::=
  <column name list>