RL example: Drive

[Adaickalavan]

• Added baseline example, consisting of training, inference, and zoo agent registration, for the driving and turning tasks in Driving SMARTS 2023.1 and 2023.2 benchmarks, respectively. It uses RelativeTargetPose action space.
• Documented the challenge objective, desired inference code structure, and use of baseline example, for Driving SMARTS 2023.1 (i.e., basic motion planning) and 2023.2 (i.e, turns) benchmarks.
• Added an env wrapper for constraining the relative target pose action range.