IMPALA-945: Fix column reordering with SELECT expressions

Previously, to produce the correct output expressions for the root plan
fragment before a table sink, InsertStmt would reorder the result
expressions for the query statement at the plan root. This had stopped
working for SelectStmts (and test coverage didn't catch that).

Now InsertStmt produces its own output expressions that can substitute
for the originals from the query statement, and the planner uses those
instead.

All query tests for column reordering have been duplicated to use SELECT
expressions.

Change-Id: Ib909fe35d27416b33ba2e5ac797aa931e1fe43f9
Reviewed-on: http://gerrit.ent.cloudera.com:8080/2204
Tested-by: jenkins
Reviewed-by: Henry Robinson <henry@cloudera.com>