Good to output value of actual query arguments/placeholders on completed_requests return

Currently, there is no way from completed_requests to determine the actual arguments passed to a query.

This is very helpful while running parameterized queries and debugging the actual query.

One way to do this is via debug mode for query and then getting the results, this is not viable on production systems and is cumbersome for dev systems.

Would be good to output this directly from completed_requests