[sim] Move Sim classes from HAL to wpilibc/j (#2549)

Also move some things in HAL for consistency.

WAS:
C++:
- C APIs: #include "mockdata/AccelerometerData.h"
- User side class: #include "simulation/AccelerometerSim.h"
Java:
- JNI APIs: hal.sim.mockdata.AccelerometerData (and a few classes in hal.sim)
- User side classes: hal.sim.AccelerometerSim

IS:
C++:
- C APIs: #include "hal/simulation/AccelerometerData.h"
- C++ class: #include "frc/simulation/AccelerometerSim.h"
Java:
- JNI APIs: hal.simulation.AccelerometerData
- User side class: wpilibj.simulation.AccelerometerSim

wpilibc/src/main/native/include/frc/simulation/DigitalPWMSim.h

@@ -0,0 +1,74 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2018-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <memory>
+#include <utility>
+
+#include <hal/simulation/DigitalPWMData.h>
+
+#include "CallbackStore.h"
+
+namespace frc {
+namespace sim {
+class DigitalPWMSim {
+ public:
+  explicit DigitalPWMSim(int index) { m_index = index; }
+
+  std::unique_ptr<CallbackStore> RegisterInitializedCallback(
+      NotifyCallback callback, bool initialNotify) {
+    auto store = std::make_unique<CallbackStore>(
+        m_index, -1, callback, &HALSIM_CancelDigitalPWMInitializedCallback);
+    store->SetUid(HALSIM_RegisterDigitalPWMInitializedCallback(
+        m_index, &CallbackStoreThunk, store.get(), initialNotify));
+    return store;
+  }
+
+  bool GetInitialized() const {
+    return HALSIM_GetDigitalPWMInitialized(m_index);
+  }
+
+  void SetInitialized(bool initialized) {
+    HALSIM_SetDigitalPWMInitialized(m_index, initialized);
+  }
+
+  std::unique_ptr<CallbackStore> RegisterDutyCycleCallback(
+      NotifyCallback callback, bool initialNotify) {
+    auto store = std::make_unique<CallbackStore>(
+        m_index, -1, callback, &HALSIM_CancelDigitalPWMDutyCycleCallback);
+    store->SetUid(HALSIM_RegisterDigitalPWMDutyCycleCallback(
+        m_index, &CallbackStoreThunk, store.get(), initialNotify));
+    return store;
+  }
+
+  double GetDutyCycle() const { return HALSIM_GetDigitalPWMDutyCycle(m_index); }
+
+  void SetDutyCycle(double dutyCycle) {
+    HALSIM_SetDigitalPWMDutyCycle(m_index, dutyCycle);
+  }
+
+  std::unique_ptr<CallbackStore> RegisterPinCallback(NotifyCallback callback,
+                                                     bool initialNotify) {
+    auto store = std::make_unique<CallbackStore>(
+        m_index, -1, callback, &HALSIM_CancelDigitalPWMPinCallback);
+    store->SetUid(HALSIM_RegisterDigitalPWMPinCallback(
+        m_index, &CallbackStoreThunk, store.get(), initialNotify));
+    return store;
+  }
+
+  int GetPin() const { return HALSIM_GetDigitalPWMPin(m_index); }
+
+  void SetPin(int pin) { HALSIM_SetDigitalPWMPin(m_index, pin); }
+
+  void ResetData() { HALSIM_ResetDigitalPWMData(m_index); }
+
+ private:
+  int m_index;
+};
+}  // namespace sim
+}  // namespace frc