Support large agent vehicles controlled by OpEn

[liamchzh]

Social vehicles can be buses or trucks, likewise, agents can also be specified a vehicle type.

Maybe starts with discrete action space?

[Gamenot]

@iman512003 @davidrusu Pair over it.

[iman512003]

Breaking this issue to multiple issues:

1-1)create a urdf file for large vehicle model.
1-2)Expose vehicle type at the agent interface level.

2-1)make sure that the trajectory tracking controller works with the new urdf model.

3-1) To make OpEn with large vehicle whether it is kinematic/dyanmics

[iman512003]

closed in favor of #198 ,#199, #200 .