Autonomous Command: Drive X Distance

Implement a drivetrain command to drive a certain distance X (forward or backward).

Use the Talon closed loop control mode for setting position.

Refer to the Phoenix documentation for guidelines, and/or see how it was done in the 2019 code.

https://phoenix-documentation.readthedocs.io/en/latest/ch16_ClosedLoop.html

This may involve some PID tuning on the drivebase. Be careful :)
