Complete Centrallix SQL tests

[sheesania]

CXSQL tests that still need to be completed:

• tests for remaining SQL functions and operators (summer 2020 was focused on string functions)
• tests for remaining SQL clauses -- currently, we have coverage of collections, joins, and the "on duplicate" clause for inserts. we'd need:
  • INSERT ... SELECT statements (more complete, there is some coverage with the on duplicate tests)
  • DELETE statements
  • UPDATE statements (including updating through a join)
  • SELECT with GROUP BY (including two-level/nested aggregates)
  • SELECT with ORDER BY
  • SELECT without a FROM (i.e. selecting constants)
  • query scope collections
  • declared objects, including setting and using declared object properties, on both application scope and query scope
  • subqueries