[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/SimDeviceSim.h

@@ -0,0 +1,80 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019-2020 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 <functional>
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <hal/SimDevice.h>
+#include <hal/simulation/SimDeviceData.h>
+
+#include "CallbackStore.h"
+
+namespace frc {
+namespace sim {
+class SimDeviceSim {
+ public:
+  explicit SimDeviceSim(const char* name)
+      : m_handle{HALSIM_GetSimDeviceHandle(name)} {}
+
+  hal::SimValue GetValue(const char* name) const {
+    return HALSIM_GetSimValueHandle(m_handle, name);
+  }
+
+  hal::SimDouble GetDouble(const char* name) const {
+    return HALSIM_GetSimValueHandle(m_handle, name);
+  }
+
+  hal::SimEnum GetEnum(const char* name) const {
+    return HALSIM_GetSimValueHandle(m_handle, name);
+  }
+
+  hal::SimBoolean GetBoolean(const char* name) const {
+    return HALSIM_GetSimValueHandle(m_handle, name);
+  }
+
+  static std::vector<std::string> GetEnumOptions(hal::SimEnum val) {
+    int32_t numOptions;
+    const char** options = HALSIM_GetSimValueEnumOptions(val, &numOptions);
+    std::vector<std::string> rv;
+    rv.reserve(numOptions);
+    for (int32_t i = 0; i < numOptions; ++i) rv.emplace_back(options[i]);
+    return rv;
+  }
+
+  template <typename F>
+  void EnumerateValues(F callback) const {
+    return HALSIM_EnumerateSimValues(
+        m_handle, &callback,
+        [](const char* name, void* param, HAL_SimValueHandle handle,
+           HAL_Bool readonly, const struct HAL_Value* value) {
+          std::invoke(*static_cast<F*>(param), name, handle, readonly, value);
+        });
+  }
+
+  operator HAL_SimDeviceHandle() const { return m_handle; }
+
+  template <typename F>
+  static void EnumerateDevices(const char* prefix, F callback) {
+    return HALSIM_EnumerateSimDevices(
+        prefix, &callback,
+        [](const char* name, void* param, HAL_SimDeviceHandle handle) {
+          std::invoke(*static_cast<F*>(param), name, handle);
+        });
+  }
+
+  static void ResetData() { HALSIM_ResetSimDeviceData(); }
+
+ private:
+  HAL_SimDeviceHandle m_handle;
+};
+}  // namespace sim
+}  // namespace frc