fix Safari on macOS native prompt with custom link

macOS Safari requires a user gesture to show the native prompt, and
doesn't allow disk I/O in the Promise.
Switched to the opted in check to use optedIn since this uses a cached
value which doesn't have this disk I/O issue.

src/shared/managers/CustomLinkManager.ts

@@ -146,9 +146,7 @@ export class CustomLinkManager {
   }
 
   private async handleClick(element: HTMLElement): Promise<void> {
-    const isPushEnabled =
-      await OneSignal.context.subscriptionManager.isPushNotificationsEnabled();
-    if (isPushEnabled) {
+    if (OneSignal.User.PushSubscription.optedIn) {
       await OneSignal.User.PushSubscription.optOut();
       await this.setTextFromPushStatus(element);
     } else {