[nit] rename FlutterRegistrarResponder class

* Now that it is not a Registrar, the name is misleading, rename to `FlutterMessengerResponder`

Author: nan-li

android/src/main/java/com/onesignal/flutter/FlutterRegistrarResponder.java renamed to android/src/main/java/com/onesignal/flutter/FlutterMessengerResponder.java

@@ -11,7 +11,7 @@
 import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugin.common.MethodChannel;
 
-abstract class FlutterRegistrarResponder {
+abstract class FlutterMessengerResponder {
    Context context;
    protected MethodChannel channel;
    BinaryMessenger messenger;

android/src/main/java/com/onesignal/flutter/OneSignalDebug.java

@@ -16,7 +16,7 @@
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.MethodChannel.Result;
 
-public class OneSignalDebug extends FlutterRegistrarResponder implements MethodCallHandler {
+public class OneSignalDebug extends FlutterMessengerResponder implements MethodCallHandler {
 
    static void registerWith(BinaryMessenger messenger) {
         OneSignalDebug controller = new OneSignalDebug();

android/src/main/java/com/onesignal/flutter/OneSignalInAppMessages.java

@@ -22,7 +22,7 @@
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.MethodChannel.Result;
 
-public class OneSignalInAppMessages extends FlutterRegistrarResponder implements MethodCallHandler, 
+public class OneSignalInAppMessages extends FlutterMessengerResponder implements MethodCallHandler, 
 IInAppMessageClickListener, IInAppMessageLifecycleListener{
 
     static void registerWith(BinaryMessenger messenger) {

android/src/main/java/com/onesignal/flutter/OneSignalLocation.java

@@ -16,7 +16,7 @@
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.MethodChannel.Result;
 
-public class OneSignalLocation extends FlutterRegistrarResponder implements MethodCallHandler {
+public class OneSignalLocation extends FlutterMessengerResponder implements MethodCallHandler {
 
     static void registerWith(BinaryMessenger messenger) {
         OneSignalLocation controller = new OneSignalLocation();

android/src/main/java/com/onesignal/flutter/OneSignalNotifications.java

@@ -34,7 +34,7 @@
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.MethodChannel.Result;
 
-public class OneSignalNotifications extends FlutterRegistrarResponder implements MethodCallHandler, INotificationClickListener, INotificationLifecycleListener, IPermissionObserver {
+public class OneSignalNotifications extends FlutterMessengerResponder implements MethodCallHandler, INotificationClickListener, INotificationLifecycleListener, IPermissionObserver {
     private final HashMap<String, INotificationWillDisplayEvent> notificationOnWillDisplayEventCache = new HashMap<>();
     private final HashMap<String, INotificationWillDisplayEvent> preventedDefaultCache = new HashMap<>();
 

android/src/main/java/com/onesignal/flutter/OneSignalPlugin.java

@@ -26,7 +26,7 @@
 import io.flutter.plugin.common.MethodChannel.Result;
 
 /** OnesignalPlugin */
-public class OneSignalPlugin extends FlutterRegistrarResponder implements FlutterPlugin, MethodCallHandler, ActivityAware {
+public class OneSignalPlugin extends FlutterMessengerResponder implements FlutterPlugin, MethodCallHandler, ActivityAware {
 
   public OneSignalPlugin() {
   }

android/src/main/java/com/onesignal/flutter/OneSignalPushSubscription.java

@@ -22,7 +22,7 @@
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.MethodChannel.Result;
 
-public class OneSignalPushSubscription extends FlutterRegistrarResponder implements MethodCallHandler, IPushSubscriptionObserver {
+public class OneSignalPushSubscription extends FlutterMessengerResponder implements MethodCallHandler, IPushSubscriptionObserver {
 
     static void registerWith(BinaryMessenger messenger) {
         OneSignalPushSubscription controller = new OneSignalPushSubscription();

android/src/main/java/com/onesignal/flutter/OneSignalSession.java

@@ -11,7 +11,7 @@
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.MethodChannel.Result;
 
-public class OneSignalSession extends FlutterRegistrarResponder implements MethodCallHandler {
+public class OneSignalSession extends FlutterMessengerResponder implements MethodCallHandler {
 
     static void registerWith(BinaryMessenger messenger) {
         OneSignalSession controller = new OneSignalSession();

android/src/main/java/com/onesignal/flutter/OneSignalUser.java

@@ -19,7 +19,7 @@
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.MethodChannel.Result;
 
-public class OneSignalUser extends FlutterRegistrarResponder implements MethodCallHandler, IUserStateObserver {
+public class OneSignalUser extends FlutterMessengerResponder implements MethodCallHandler, IUserStateObserver {
 
     static void registerWith(BinaryMessenger messenger) {
         OneSignalUser controller = new OneSignalUser();