[US-19] Convert Joystick speed.msg into geometry_msgs/Twist.msg

[JoshuaGabriel]

I want to remove the custom message we created for the runt rover (speed.msg) to ros supported geometry_msgs/Twist.msg.

Speed.msg
int64 leftspeed
int64 rightspeed
int64 leftdirection
int64 rightdirection

while Twist.msg
Vector3 linear
Vector3 angular

Vector3 has x,y,z

1. The joystick node transforms joystick data into speed.msg, so that needs to change to Twist.msg
2. Arduino code for drivetrain takes in speed.msg, so we need to change that to Twist.msg

We are doing this to

• Avoid complexity with handling a custom message
• Twist is supported by navigation stack that we might look to implement later on

[JoshuaGabriel]

Can we double-check if we need to do any math on the Arduino? If the calculation from twist.msg to PWM is memory intensive on the arduino then I rather not do this