Support the AS keyword in actual SQL statements.

If you have a query such as the following:

`SELECT (a.name, b.name AS bname) AS (&fooStruct.*) FROM test`

SQLAir complains on the first AS to get the column name changed and avoid conflict. It would be nice if this was support as it avoids having to unpack all the columns individually and the subsequent blowout in SELECT statement verbosity. The other way of currently working around this is to build a view as well.