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/Document/document.schema.ts

@@ -447,9 +447,6 @@ export class DocumentSchema extends PothosSchema {
           if (!ctx.isSubscription) {
             throw new Error('Not allowed')
           }
-          const {
-            websocket: { pubSub },
-          } = ctx
           const documentId = args.documentId
           // check user permission
           const document = await this.prisma.document.findUnique({
@@ -469,7 +466,7 @@ export class DocumentSchema extends PothosSchema {
               throw new Error('User is not owner or collaborator of document')
             }
           }
-          return pubSub.asyncIterableIterator([
+          return ctx.websocket.pubSub.asyncIterator([
             `${DocumentEvent.CHANGED}.${documentId}`,
             `${DocumentEvent.DELETED}.${documentId}`,
             `${DocumentEvent.SAVED}.${documentId}`,