fix(type): Make badge NSNumber instead of NSInteger

* This let's us differentiate between null vs 0. The payload from APNS will be already be an NSNumber: https://developer.apple.com/documentation/usernotifications/unnotificationcontent/badge?language=objc
* This fixes a bug when a notification had "SetTo" = 0, our check for the existence of notification.badge could not differentiate null vs 0, and we detected 0 as lack of existence.
* Note: we will still cache and read badge count (ONESIGNAL_BADGE_KEY) as NSInteger since that is what we have been doing, and avoid having to change types / migration.

Author: nan-li

iOS_SDK/OneSignalSDK/OneSignalCore/Source/OSNotification.h

@@ -59,7 +59,7 @@
 @property(readonly, nullable)NSString* category;
 
 /* The badge assigned to the application icon */
-@property(readonly)NSInteger badge;
+@property(readonly, nullable)NSNumber* badge;
 @property(readonly)NSInteger badgeIncrement;
 
 /* The sound parameter passed to the notification

iOS_SDK/OneSignalSDK/OneSignalCore/Source/OSNotification.m

@@ -124,7 +124,7 @@ - (void)parseCommonOneSignalFields:(NSDictionary*)payload {
 
 - (void)parseApnsFields {
     [self parseAlertField:_rawPayload[@"aps"][@"alert"]];
-    _badge = [_rawPayload[@"aps"][@"badge"] intValue];
+    _badge = _rawPayload[@"aps"][@"badge"];
     _sound = _rawPayload[@"aps"][@"sound"];
 }
 
@@ -145,7 +145,7 @@ - (void)parseAlertField:(NSObject*)alert {
 // May also be used if OneSignal server hasn't received the SDK version 2.4.0+ update event
 - (void)parseRemoteSlient:(NSDictionary*)payload {
     [self parseAlertField:payload[@"m"]];
-    _badge = [payload[@"b"] intValue];
+    _badge = payload[@"b"];
     _sound = payload[@"s"];
     _attachments = payload[@"at"];
     [self parseActionButtons:payload[@"o"]];
@@ -258,7 +258,7 @@ - (NSDictionary *)jsonRepresentation {
         [obj setObject:self.templateId forKeyedSubscript: @"templateId"];
 
     if (self.badge)
-        [obj setObject:@(self.badge) forKeyedSubscript: @"badge"];
+        [obj setObject:self.badge forKeyedSubscript: @"badge"];
 
     if (self.badgeIncrement)
         [obj setObject:@(self.badgeIncrement) forKeyedSubscript: @"badgeIncrement"];

iOS_SDK/OneSignalSDK/OneSignalExtension/OneSignalExtensionBadgeHandler.m

@@ -35,7 +35,7 @@ + (void)handleBadgeCountWithNotificationRequest:(UNNotificationRequest *)request
     //make sure the OneSignal cached value is updated to this value
     if (!notification.badgeIncrement) {
         if (notification.badge)
-            [OneSignalExtensionBadgeHandler updateCachedBadgeValue:notification.badge];
+            [OneSignalExtensionBadgeHandler updateCachedBadgeValue:notification.badge.intValue];
 
         return;
     }