refactor(nbstore): improve doc state management (#12359)

Move the `waitForSynced` method from `frontend` to `nbstore worker` to make the wait more reliable

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **New Features**
  - Added explicit tracking of document updating state to indicate when data is being applied or saved.
  - Introduced new methods to wait for update and synchronization completion with abort support.

- **Improvements**
  - Applied throttling with leading and trailing emissions to state observables for smoother UI updates.
  - Refined synchronization waiting logic for clearer separation between update completion and sync completion.
  - Removed throttling in workspace selector component for more immediate state feedback.
  - Updated import and clipper services to use the new synchronization waiting methods.
  - Simplified asynchronous waiting logic in indexer synchronization methods.

- **Bug Fixes**
  - Enhanced accuracy and reliability of document update and sync status indicators.

- **Tests**
  - Increased wait timeout in avatar selection test to improve stability.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/common/nbstore/src/worker/ops.ts

@@ -102,6 +102,7 @@ interface GroupedWorkerOps {
   docSync: {
     state: [void, DocSyncState];
     docState: [string, DocSyncDocState];
+    waitForSynced: [string | null, void];
     addPriority: [{ docId: string; priority: number }, boolean];
     resetSync: [void, void];
   };