Update KBH FT990 Fuel Tender

Hey everyone!

After learning how to do some wear and dirt textures we re-visited the KBH fuel tender we did late in 2025.

We have added custom dirt and wear maps to it.
Also added a script that has you start the engine before you can refuel. It consumes fuel when it is running. Adding some realism to the game.
Brake lights have also been added.