Write ROS throttle & brake control node

[wheitman]

Subscribes to /carla/hero/vehicle_control_cmd with message type CarlaEgoVehicleControl.

Then sends commands to throttle and brake systems. Merges the work of brake-by-wire and throttle-by-wire.

• [ ] Add throttle by wire to MCU
• [ ] Add communication between MCU and OBC to establish throttle by wire through ROS.
• [ ] Once brake system is wired and mounted, add brake-by-wire functionalty
• [ ] Embded safety checks to disable both systems if a fault occurs

[wheitman]

@jaiperis has added a throttle control package, though it is still in the beginning stages. The brake control node needs to be written, but we can use @ashwin-som 's EPAS node as a starting point.