[SUGGESTION] Back engine attribute in vehicles.lua

[CodeRedDev]

Problem

Currently it is kind of a hassle to include back engine vehicles the right way in QBCore. QB-Inventory, QB-Target and QB-VehicleFailure all provide their own list of vehicles with back engines. This causes an enormous overhead.

Feature description

Back engine vehicles should be marked as such in the vehicles.lua by an attribute like ['backEngine'] = true. On no back engine vehicles this attribute can be omitted (nil == false).