fix "Hide bell if user is subscribed" option

Option that can be set in dashboard when configuring the bell. Updated
to the new v16 function. Also corrected type that was incorrect for
displayPredicate

src/shared/helpers/ConfigHelper.ts

@@ -532,14 +532,7 @@ export class ConfigHelper {
             enable: serverConfig.config.staticPrompts.bell.enabled,
             displayPredicate: serverConfig.config.staticPrompts.bell
               .hideWhenSubscribed
-              ? () => {
-                  return OneSignal.isPushNotificationsEnabled().then(
-                    (isPushEnabled: boolean) => {
-                      /* The user is subscribed, so we want to return "false" to hide the notify button */
-                      return !isPushEnabled;
-                    },
-                  );
-                }
+              ? () => !OneSignal.User.PushSubscription.optedIn
               : null,
             size: serverConfig.config.staticPrompts.bell.size,
             position: serverConfig.config.staticPrompts.bell.location,

src/shared/models/Prompts.ts

@@ -123,7 +123,7 @@ export interface BellText {
 export interface AppUserConfigNotifyButton {
   options?: AppUserConfigNotifyButton;
   enable: boolean;
-  displayPredicate?: () => void | null | undefined;
+  displayPredicate?: null | (() => void | null | undefined | boolean);
   size?: BellSize;
   position?: BellPosition;
   offset?: { bottom: string; left: string; right: string };