Implement PID controller to hold arm at specific position

[jdlanning]

Now that we are directly connecting the absolute encoder to the SparkMax we can use the internal PID controller inside the SparkMax to hold the Arm position

Here is an example of PID feedback. However it use a Relative encode instead of an Absolute

https://github.com/REVrobotics/SPARK-MAX-Examples/blob/master/Java/Alternate%20Encoder/src/main/java/frc/robot/Robot.java

This code will need to be adapted inside of our Arm subsystem