feat(editor): add blobState$ to BlobEngine (#11756)

Closes: [BS-3137](https://linear.app/affine-design/issue/BS-3137/在-bs-添加-blobstate-接口)

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

## Summary by CodeRabbit

- **New Features**
  - Introduced real-time status tracking for file upload and download operations, allowing users to monitor progress and errors more effectively.
- **Improvements**
  - Enhanced icon display for attachments, providing a refreshed visual experience.
  - Improved update frequency and accuracy for file synchronization status indicators.
- **Bug Fixes**
  - Refined internal logic for filtering status updates, ensuring more precise feedback during file operations.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/framework/sync/src/blob/engine.ts

@@ -104,6 +104,10 @@ export class BlobEngine {
     return key;
   }
 
+  blobState$(key: string) {
+    return this.main.blobState$?.(key) ?? null;
+  }
+
   start() {
     if (this._abort) {
       return;

blocksuite/framework/sync/src/blob/source.ts

@@ -1,3 +1,12 @@
+import type { Observable } from 'rxjs';
+
+export interface BlobState {
+  uploading: boolean;
+  downloading: boolean;
+  errorMessage?: string | null;
+  overSize: boolean;
+}
+
 export interface BlobSource {
   name: string;
   readonly: boolean;
@@ -5,4 +14,6 @@ export interface BlobSource {
   set: (key: string, value: Blob) => Promise<string>;
   delete: (key: string) => Promise<void>;
   list: () => Promise<string[]>;
+  // This state is only available when uploading to the cloud or downloading from the cloud.
+  blobState$?: (key: string) => Observable<BlobState> | null;
 }