Add simulation pause/resume/step support

Calling HALSIM_PauseTiming pauses the FPGA clock and notifiers.
Calling HALSIM_ResumeTiming resumes the FPGA clock and notifiers.
Calling HALSIM_StepTiming steps the FPGA clock and runs applicable notifiers.

This will effectively pause TimedRobot and any other notifier-based events,
but of course will not pause user threads that do not use the notifier (e.g.
image processing).

hal/src/main/native/sim/jni/SimulatorJNI.cpp

@@ -142,6 +142,54 @@ Java_edu_wpi_first_hal_sim_mockdata_SimulatorJNI_restartTiming
   HALSIM_RestartTiming();
 }
 
+/*
+ * Class:     edu_wpi_first_hal_sim_mockdata_SimulatorJNI
+ * Method:    pauseTiming
+ * Signature: ()V
+ */
+JNIEXPORT void JNICALL
+Java_edu_wpi_first_hal_sim_mockdata_SimulatorJNI_pauseTiming
+  (JNIEnv*, jclass)
+{
+  HALSIM_PauseTiming();
+}
+
+/*
+ * Class:     edu_wpi_first_hal_sim_mockdata_SimulatorJNI
+ * Method:    resumeTiming
+ * Signature: ()V
+ */
+JNIEXPORT void JNICALL
+Java_edu_wpi_first_hal_sim_mockdata_SimulatorJNI_resumeTiming
+  (JNIEnv*, jclass)
+{
+  HALSIM_ResumeTiming();
+}
+
+/*
+ * Class:     edu_wpi_first_hal_sim_mockdata_SimulatorJNI
+ * Method:    isTimingPaused
+ * Signature: ()Z
+ */
+JNIEXPORT jboolean JNICALL
+Java_edu_wpi_first_hal_sim_mockdata_SimulatorJNI_isTimingPaused
+  (JNIEnv*, jclass)
+{
+  return HALSIM_IsTimingPaused();
+}
+
+/*
+ * Class:     edu_wpi_first_hal_sim_mockdata_SimulatorJNI
+ * Method:    stepTiming
+ * Signature: (J)V
+ */
+JNIEXPORT void JNICALL
+Java_edu_wpi_first_hal_sim_mockdata_SimulatorJNI_stepTiming
+  (JNIEnv*, jclass, jlong delta)
+{
+  HALSIM_StepTiming(delta);
+}
+
 /*
  * Class:     edu_wpi_first_hal_sim_mockdata_SimulatorJNI
  * Method:    resetHandles