Use cx_Oracle dml_ret_array_val

Use cx_Oracle dml_ret_array_val

Fixed issue for cx_Oracle 7.0 where the behavior of Oracle param.getvalue()
now returns a list, rather than a single scalar value, breaking
autoincrement logic throughout the Core and ORM. The dml_ret_array_val
compatibility flag is used for cx_Oracle 6.3 and 6.4 to establish compatible
behavior with 7.0 and forward, for cx_Oracle 6.2.1 and prior a version
number check falls back to the old logic.

Fixes: #4335
Change-Id: Ia60f5514803a505898c1ac9252355990c6203dda