[wpilib] Remove PIDController, PIDOutput, PIDSource

Move them to the old commands vendordep so that PIDCommand and PIDSubsystem
continue to work.

This also removes Filter and LinearDigitalFilter.

wpilibcExamples/src/main/cpp/examples/ArmBotOffboard/include/ExampleSmartMotorController.h

@@ -79,6 +79,4 @@ class ExampleSmartMotorController : public frc::SpeedController {
   void Disable() override {}
 
   void StopMotor() override {}
-
-  void PIDWrite(double output) override {}
 };