create system test for drivetrain that mirrors current manual system test

[gcschmit]

The system test for the drivetrain and swerve modules is very basic and doesn't actually test any code in the drivetrain class. A more robust system test would mirror what we current test by hand as part of the pit checklist. That is the system test could perform and verify the following:

• drive left (check swerve angle and velocity for each of the following)
• drive right
• drive forward
• drive backward
• rotate clockwise
• rotate counterclockwise

I also think it would be good to incorporate the gyro into the drivetrain system test. I'm not sure how to do this. Perhaps it just prompts (via a beep?) us to rotate the robot clockwise and counterclockwise and verifies that the gyro angle is decreasing/increasing.