refactor(density): Remove density/calmai/cargens.

[Randolio]

Description

Removes the density, calm ai and car gen portion of small resources and merges it into it's own resource. It used to be the case that when you restarted small resources, it would cause a minor freeze for a second and delete all current vehicles in traffic so it would make sense for this resource to be on it's own as it rarely gets touched. Hence why I combined the car gen maps and the calm ai. Link to the new repository is here: https://github.com/Qbox-project/qbx_density but it's currently private incase you decide "Nah Randolio, not happening mate". (Not really sure the process of adding new resources to the project)

Checklist

• [x] I have personally loaded this code into an updated Qbox project and checked all of its functionality.
• [x] My pull request fits the contribution guidelines & code conventions.

[mafewtm]

Don't merge until we hear back from Manason