fix: SELECT now() returns current time.

[vrongmeal]

glaredb=> select now();
             now()
-------------------------------
 2023-08-07 20:35:57.042442+00
(1 row)

Fixes #1427

[vrongmeal]

TBH, not completely happy with this. I want to create another wrapper to handle everything related to the "execution of a query", basically one state for one execution. This works but creates a copy of the state each time. The only thing the copy has different is the query_execution_start_time, which we wanted.

Not closing #1432 to keep track of this.