[wpilib] Simulation: Add ctor parameter to set starting state of mechanism sims (#5288)

- Add a constructor parameter to configure the initial angle of the arm
- Also reorganizes cascading constructors for Java

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/examples/armsimulation/subsystems/Arm.java

@@ -50,6 +50,7 @@ public class Arm implements AutoCloseable {
           Constants.kMinAngleRads,
           Constants.kMaxAngleRads,
           true,
+          0,
           VecBuilder.fill(Constants.kArmEncoderDistPerPulse) // Add noise with a std-dev of 1 tick
           );
   private final EncoderSim m_encoderSim = new EncoderSim(m_encoder);

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/examples/elevatorsimulation/subsystems/Elevator.java

@@ -54,6 +54,7 @@ public class Elevator implements AutoCloseable {
           Constants.kMinElevatorHeightMeters,
           Constants.kMaxElevatorHeightMeters,
           true,
+          0,
           VecBuilder.fill(0.01));
   private final EncoderSim m_encoderSim = new EncoderSim(m_encoder);
   private final PWMSim m_motorSim = new PWMSim(m_motor);