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This addresses some of the desync causes:

* `vehicle_create_car` was using `scenario_rand` when it shouldn't have
* ghost elements affected grass growth
* ghost elements affecting peep logic[1]

It also adds some desync debug facilities, enabled at compile time.

It also reverts part of change introduced in
https://github.com/OpenRCT2/OpenRCT2/pull/5185,
namely reorder of desync check vs call to `ProcessGameCommandQueue();`

[1] It is not ideal to have this check in multiple locations, it is prone
to human error. We already have `map_remove_provisional_elements`,
but it is possible it does not work as well as it should. This needs
further investigation.