chore: refactor pub/sub iterator usage across schema files

- Updated pub/sub iterator methods from `asyncIterableIterator` to `asyncIterator` in multiple schema files for improved compatibility with the latest GraphQL subscriptions.
- Refactored subscription logic in CollaborationSession, Document, Message, User, and other schema files to enhance readability and maintainability.
- Adjusted imports in GraphQL builder to utilize RedisPubSub for better performance in subscription handling.

src/CollaborationSession/collaborationsession.schema.ts

@@ -324,7 +324,9 @@ export class CollaborationSessionSchema extends PothosSchema {
           if (!collaborationSession) {
             throw new Error('Collaboration session not found')
           }
-          return ctx.websocket.pubSub.asyncIterableIterator(`collaborationSessionUpdated:${collaborationSession.id}`)
+          return ctx.websocket.pubSub.asyncIterator([
+            `collaborationSessionUpdated:${collaborationSession.id}`,
+          ]) as unknown as AsyncIterable<CollaborationSession>
         },
         resolve: async (payload: CollaborationSession) => payload,
       }),