feat(core): duplicated calendar subscription notification (#12364)

packages/frontend/core/src/modules/integration/entities/calendar.ts

@@ -106,6 +106,10 @@ export class CalendarIntegration extends Entity {
     }
   }
 
+  getSubscription(url: string) {
+    return this.store.getSubscription(url);
+  }
+
   deleteSubscription(url: string) {
     this.store.removeSubscription(url);
   }

packages/frontend/core/src/modules/integration/store/calendar.ts

@@ -99,6 +99,10 @@ export class CalendarStore extends Store {
     );
   }
 
+  getSubscription(url: string) {
+    return this.getSubscriptionMap()[url];
+  }
+
   watchSubscriptionCache(url: string) {
     return this.cacheStorage.watch<string>(this.getCacheKey(url));
   }