fix: Write vehicle mass into properties of entity

With the update of the scenario_api property.mass is now available and the corresponding assignment is added in the EntityCreator.

Note that the patch is clearly visible in the EntityCreator inside the existing_open_scenario_engine, where it originates from. Transferring it to the (generated) engine looks like a bigger change, but in fact it's only a copy of the EntityCreator matching to the current scenario_api.

Signed-off-by: Rene Paris rene.paris@in-tech.com