[oldCommands] Add wrappers for WPILib objects to work with old PID Controller (#3710)

wpilibOldCommands/src/main/native/cpp/pidwrappers/PIDAnalogInput.cpp

@@ -0,0 +1,11 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "frc/pidwrappers/PIDAnalogInput.h"
+
+using namespace frc;
+
+double PIDAnalogInput::PIDGet() {
+  return GetAverageVoltage();
+}