clearBadgeCount method does not need to return bool

* The `clearBadgeCount` was returning a bool flag to indicate if badge was set within the method. However, nothing is consuming this flag, and with the Apple API to get application icon badge number deprecated (https://developer.apple.com/documentation/uikit/uiapplication/applicationiconbadgenumber?language=objc), the SDK's ability to get accurate badge count at any particular moment is reduced.

Author: nan-li

iOS_SDK/OneSignalSDK/OneSignalNotifications/OSNotificationsManager.h

@@ -114,7 +114,7 @@ NS_SWIFT_NAME(onClick(event:));
 
 + (void)handleWillShowInForegroundForNotification:(OSNotification *_Nonnull)notification completion:(OSNotificationDisplayResponse _Nonnull)completion;
 + (void)handleNotificationActionWithUrl:(NSString* _Nullable)url actionID:(NSString* _Nonnull)actionID;
-+ (BOOL)clearBadgeCount:(BOOL)fromNotifOpened fromClearAll:(BOOL)fromClearAll;
++ (void)clearBadgeCount:(BOOL)fromNotifOpened fromClearAll:(BOOL)fromClearAll;
 
 + (BOOL)receiveRemoteNotification:(UIApplication* _Nonnull)application UserInfo:(NSDictionary* _Nonnull)userInfo completionHandler:(void (^_Nonnull)(UIBackgroundFetchResult))completionHandler;
 + (void)notificationReceived:(NSDictionary* _Nonnull)messageDict wasOpened:(BOOL)opened;

iOS_SDK/OneSignalSDK/OneSignalNotifications/OSNotificationsManager.m

@@ -784,7 +784,7 @@ + (void)displayWebView:(NSURL*)url {
     openUrlBlock(true);
 }
 
-+ (BOOL)clearBadgeCount:(BOOL)fromNotifOpened fromClearAll:(BOOL)fromClearAll {
++ (void)clearBadgeCount:(BOOL)fromNotifOpened fromClearAll:(BOOL)fromClearAll {
 
     NSNumber *disableBadgeNumber = [[NSBundle mainBundle] objectForInfoDictionaryKey:ONESIGNAL_DISABLE_BADGE_CLEARING];
 
@@ -796,7 +796,7 @@ + (BOOL)clearBadgeCount:(BOOL)fromNotifOpened fromClearAll:(BOOL)fromClearAll {
     if (_disableBadgeClearing && !fromClearAll) {
         // The customer could have manually changed the badge value. We must ensure our cached value will match the current state.
         [OneSignalUserDefaults.initShared saveIntegerForKey:ONESIGNAL_BADGE_KEY withValue:[UIApplication sharedApplication].applicationIconBadgeNumber];
-        return false;
+        return;
     }
 
     bool wasBadgeSet = [UIApplication sharedApplication].applicationIconBadgeNumber > 0;
@@ -806,8 +806,6 @@ + (BOOL)clearBadgeCount:(BOOL)fromNotifOpened fromClearAll:(BOOL)fromClearAll {
             [[UIApplication sharedApplication] setApplicationIconBadgeNumber:0];
         }];
     }
-
-    return wasBadgeSet;
 }
 
 + (BOOL)handleIAMPreview:(OSNotification *)notification {