* Use window functions for SQL drivers for cumulative count and sum

* H2/Snowflake/Redshift implementation

* Test fixes 

* Use SELECT expression positions as the default window function implementation

* Some test fixes.

* Fix bugs in add-alias-info

* MongoDB fixes

* Another pass

* BigQuery should use positions?

* Disable tests for the failing drivers, we can fix in follow-on PRs.

* Extra info

* Add GH issue numbers

* Update more GH issue numbers

* Fix SQL Server!!!! wooo

* I THOUGHT WE WERE DISABLING SPARK SQL!!!!!!!!!!1

* Cleanup to get things ready for review.

* Snowflake + Vertica shouldn't use output column numbers for ORDER BY in OVER

* Code cleanup

* Test fix?