[sim] Add Java wrapper for getProgramStarted (#2566)

Also move SimHooks to wpilibj (to match wpilibc).

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

@@ -146,6 +146,18 @@ Java_edu_wpi_first_hal_simulation_SimulatorJNI_setProgramStarted
   HALSIM_SetProgramStarted();
 }
 
+/*
+ * Class:     edu_wpi_first_hal_simulation_SimulatorJNI
+ * Method:    getProgramStarted
+ * Signature: ()Z
+ */
+JNIEXPORT jboolean JNICALL
+Java_edu_wpi_first_hal_simulation_SimulatorJNI_getProgramStarted
+  (JNIEnv*, jclass)
+{
+  return HALSIM_GetProgramStarted();
+}
+
 /*
  * Class:     edu_wpi_first_hal_simulation_SimulatorJNI
  * Method:    restartTiming