Rewrite handling of actions when JS is not yet initialized.

We have to save initial notification action response
in case there isn't registered any FCMNotificationReceived
event handler yet. For example when the app is killed by a user
so JS has to be initialized first. The saved action
response will be sent to JS after first
FCMNotificationReceived event handler registered.

ios/RNFIRMessaging.m

@@ -217,26 +217,7 @@ RCT_MULTI_ENUM_CONVERTER(UNNotificationCategoryOptions, (@{
 
 @end
 
-@interface RNFIRMessagingHelper : NSObject
-
-@property (nonatomic, retain) NSDictionary *lastNotificationResponse;
-
-+ (nonnull instancetype) sharedInstance;
-
-@end
-
-@implementation RNFIRMessagingHelper
-
-+ (nonnull instancetype)sharedInstance {
-    static RNFIRMessagingHelper *sharedInstance = nil;
-    static dispatch_once_t onceToken;
-    dispatch_once(&onceToken, ^{
-        sharedInstance = [self new];
-    });
-    return sharedInstance;
-}
-
-@end
+static NSDictionary *initialNotificationActionResponse;
 
 @interface RNFIRMessaging ()
 @property (nonatomic, strong) NSMutableDictionary *notificationCallbacks;
@@ -282,7 +263,13 @@ RCT_EXPORT_MODULE();
     }
     
     NSDictionary *userInfo = @{@"data": data, @"completionHandler": completionHandler};
-    [RNFIRMessagingHelper sharedInstance].lastNotificationResponse = userInfo;
+
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        if (data[@"_actionIdentifier"] && ![data[@"_actionIdentifier"] isEqualToString:UNNotificationDefaultActionIdentifier]) {
+            initialNotificationActionResponse = userInfo;
+        }
+    });
 
     [[NSNotificationCenter defaultCenter] postNotificationName:FCMNotificationReceived object:self userInfo:userInfo];
 }
@@ -325,9 +312,11 @@ RCT_EXPORT_MODULE();
     return self;
 }
 
--(void)startObserving {
-    if([RNFIRMessagingHelper sharedInstance].lastNotificationResponse) {
-        [[NSNotificationCenter defaultCenter] postNotificationName:FCMNotificationReceived object:self userInfo:[RNFIRMessagingHelper sharedInstance].lastNotificationResponse];
+-(void) addListener:(NSString *)eventName {
+    [super addListener:eventName];
+    
+    if([eventName isEqualToString:FCMNotificationReceived] && initialNotificationActionResponse) {
+        [[NSNotificationCenter defaultCenter] postNotificationName:FCMNotificationReceived object:self userInfo:[initialNotificationActionResponse copy]];
     }
 }
 
@@ -351,6 +340,8 @@ RCT_EXPORT_METHOD(getInitialNotification:(RCTPromiseResolveBlock)resolve rejecte
     }
 }
 
+
+
 RCT_EXPORT_METHOD(getAPNSToken:(RCTPromiseResolveBlock)resolve rejecter:(RCTPromiseRejectBlock)reject)
 {
     NSData * deviceToken = [FIRMessaging messaging].APNSToken;
@@ -628,7 +619,9 @@ RCT_EXPORT_METHOD(finishNotificationResponse: (NSString *)completionHandlerId){
 
     [self sendEventWithName:FCMNotificationReceived body:data];
 
-    [RNFIRMessagingHelper sharedInstance].lastNotificationResponse = nil;
+    if (initialNotificationActionResponse) {
+        initialNotificationActionResponse = nil;
+    }
 }
 
 - (void)sendDataMessageFailure:(NSNotification *)notification