Fixed compiling issues on AndroidX.

Author: phongcao

android/src/main/java/com/azure/reactnative/notificationhub/ReactNativeNotificationHubModule.java

@@ -6,7 +6,7 @@
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.os.Bundle;
-import android.support.v4.content.LocalBroadcastManager;
+import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 
 import com.facebook.react.bridge.LifecycleEventListener;
 import com.facebook.react.modules.core.DeviceEventManagerModule;

android/src/main/java/com/azure/reactnative/notificationhub/ReactNativeNotificationsHandler.java

@@ -17,12 +17,10 @@
 import android.net.Uri;
 import android.os.Build;
 import android.os.Bundle;
-import android.support.v4.app.NotificationCompat;
-import android.support.v4.content.LocalBroadcastManager;
+import androidx.core.app.NotificationCompat;
+import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 import android.util.Log;
 
-import com.facebook.react.bridge.ReadableMap;
-
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;

android/src/main/java/com/azure/reactnative/notificationhub/ReactNativeRegistrationIntentService.java

@@ -2,7 +2,7 @@
 
 import android.app.IntentService;
 import android.content.Intent;
-import android.support.v4.content.LocalBroadcastManager;
+import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 import android.util.Log;
 
 import com.google.android.gms.tasks.OnSuccessListener;