Shutdown ExecutorService instances on post test

* Stalling would happen on stopAllOSThreads() where it would
continue to try to call interrupt() on a OS_PENDING_EXECUTOR_ thread
over and over. The thread can't be interrupted as an Android
ExecutorService will catch it.
* Added a shutdownNow() call to OSTaskController that tests can run to
correctly shutdown the pending tasks so it's thread can be stopped.

Author: jkasten2

OneSignalSDK/onesignal/src/main/java/com/onesignal/OSTaskController.java

@@ -105,6 +105,12 @@ ConcurrentLinkedQueue<Runnable> getTaskQueueWaitingForInit() {
         return taskQueueWaitingForInit;
     }
 
+    void shutdownNow() {
+        if (pendingTaskExecutor != null) {
+            pendingTaskExecutor.shutdownNow();
+        }
+    }
+
     private static class PendingTaskRunnable implements Runnable {
         private OSTaskController controller;
         private Runnable innerTask;

OneSignalSDK/onesignal/src/main/java/com/onesignal/OneSignal.java

@@ -3167,6 +3167,10 @@ static OSTaskController getTaskRemoteController() {
       return taskRemoteController;
    }
 
+   static OSTaskController getTaskController() {
+      return taskController;
+   }
+
    static FocusTimeController getFocusTimeController() {
       return focusTimeController;
    }

OneSignalSDK/unittest/src/test/java/com/onesignal/OneSignalPackagePrivateHelper.java

@@ -271,6 +271,11 @@ public static ConcurrentLinkedQueue<Runnable> OneSignal_taskQueueWaitingForInit(
       return OneSignal.getTaskRemoteController().getTaskQueueWaitingForInit();
    }
 
+   public static void OneSignal_OSTaskController_ShutdownNow() {
+      OneSignal.getTaskRemoteController().shutdownNow();
+      OneSignal.getTaskController().shutdownNow();
+   }
+
    public static boolean OneSignal_requiresUserPrivacyConsent() {
       return OneSignal.requiresUserPrivacyConsent();
    }

OneSignalSDK/unittest/src/test/java/com/test/onesignal/TestHelpers.java

@@ -73,6 +73,7 @@
 import java.util.Set;
 
 import static com.onesignal.OneSignalPackagePrivateHelper.JSONUtils;
+import static com.onesignal.OneSignalPackagePrivateHelper.OneSignal_OSTaskController_ShutdownNow;
 import static junit.framework.Assert.assertEquals;
 import static org.robolectric.Shadows.shadowOf;
 
@@ -136,6 +137,7 @@ static void beforeTestInitAndCleanup() throws Exception {
 
    public static void afterTestCleanup() throws Exception {
       try {
+         OneSignal_OSTaskController_ShutdownNow();
          stopAllOSThreads();
       } catch (Exception e) {
          e.printStackTrace();