Refactor insert subquery processing into separate method

For insert-into-select testing, auto-generate lots of stored procedures with different combinations of partitioned/replicated tables.
Implement replicated/replicated support for insert-into-select.

Make PlanAssembler handle insert subqueries with same mechanism used for select subqueries

Create InsertSubPlanAssembler to help infer partitioning info for INSERT INTO SELECT statements.

Incremental changes for insert-into-select MP stored proc/ad hoc support

Minor incremental changes

Add testing for parameter-less insert into select statements.
Add testing for ad hoc insert into select statements.

Clean up partitioning inference for insert-into-select, add more tests
Merge branch 'master' into ENG-5182-insert-into-select-mp
Merge branch 'master' into ENG-5182-insert-into-select-mp
Incorporate Xin's review feedback.  Add more tests.
Merge branch 'master' into ENG-5182-insert-into-select-mp
Merge pull request #1608 from VoltDB/ENG-5182-insert-into-select-mp

INSERT INTO ... SELECT multi-partition and ad hoc support