[wpilib] PWMSpeedController.get(): Apply Inversion (#3016)

This makes get() return the value actually sent to the motor.

This is a breaking change.

wpilibc/src/main/native/cpp/PWMSpeedController.cpp

@@ -13,7 +13,7 @@ void PWMSpeedController::Set(double speed) {
 }
 
 double PWMSpeedController::Get() const {
-  return GetSpeed();
+  return GetSpeed() * (m_isInverted ? -1.0 : 1.0);
 }
 
 void PWMSpeedController::SetInverted(bool isInverted) {