IMPALA-6280: Materialize TupleIsNullPredicate for insert sorts

When a sort is inserted into a plan for an INSERT due to either the
target table being a Kudu table or the use of the 'clustered' hint,
and a TupleIsNullPredicate is present in the output of the sort, the
TupleIsNullPredicate may reference an incorrect tuple (i.e. not the
materialized sort tuple), leading to errors.

The solution is to materialize the TupleIsNullPredicate into the sort
tuple and then perform the appropriate expr substitutions, as is
already done for the case of analytic sorts.

Testing:
- Added an e2e test with a query that would previously fail.

Change-Id: I6c0ca717aa4321a5cc84edd1d5857912f8c85583
Reviewed-on: http://gerrit.cloudera.org:8080/8791
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: Impala Public Jenkins

testdata/workloads/functional-query/queries/QueryTest/insert.test

@@ -945,3 +945,14 @@ RESET alltypesnopart_insert
 ---- RESULTS
 : 100
 ====
+---- QUERY
+# IMPALA-6280: clustered with outer join, inline view, and TupleisNullPredicate
+insert into table alltypesinsert (int_col)
+partition (year, month) /*+ clustered,shuffle */
+select v.id, t1.id, t1.month from
+(select coalesce(id, 10) id from functional.alltypessmall) v
+right outer join functional.alltypestiny t1 on t1.id = v.id
+where v.id = 0
+---- RESULTS
+year=0/month=1/: 1
+====