Feature: cmd_vel with active obstacle avoidance

[mspringer1]

Hey,

I noticed when using the default cmd_vel interface, the native obstacle avoidance of the go2 is not active.

The obstacle avoidance client also offers a move function (https://support.unitree.com/home/en/developer/ObstaclesAvoidClient) so I would propose a second cmd_vel subscriber in the go2_driver with a different topic e.g. /obstacle_avoid/cmd_vel with a callback to the move function of api/obstacle_avoid/request instead of api/sport/request.

This could then be used for manual control of the robot to add more safety.