Additional fixes for chaining functions in group by

[eXigentCoder]

Previously the following would not work:

SELECT customerId,
              ROUND(sum(price),0) as roundSumPrice,
              sum(ROUND(price,0)) as sumRoundPrice
      FROM orders
      GROUP BY customerId
      ORDER BY customerId ASC

Specifically the 2nd column would throw an error but the 3rd would succed.
This PR adds support for the first case.