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

For insert-into-select testing, generate lots of single- and multi-partition stored procedures with different combinations of partitioned/replicated tables, with and without parameters.  Generate ad hoc statements too.

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.
That's very useful, thanks!  I was sure that some function like this existed and I just couldn't find it.