Is possible add AutoLockIdleVehicles config? 

How would that work? Basically the opposite of AutoUnlockIdleVehicles? I assume that would only apply if the vehicle had a lock which is unlocked. That seems like a pretty obscure use case. What problem would that feature be solving?

opposite of AutoUnlockIdleVehicles? 

no.

It blocks the codelock when the driver gets out of the car with the codelock open.

Just like Rust.
The differential would be to get out of the car and be able to unlock the codelock. and leave it unlocked.
With that it would be possible for someone else to look at the trunks.

Ok sounds reasonable