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 -->

tests/affine-local/e2e/local-first-avatar.spec.ts

@@ -33,7 +33,7 @@ test('should create a page with a local first avatar and remove it', async ({
     .nth(0)
     .getByTestId('workspace-avatar')
     .click();
-  await page.waitForTimeout(1000);
+  await page.waitForTimeout(2000);
   await page.getByTestId('workspace-name').click();
   await page
     .getByTestId('workspace-card')