feat(nbstore): add more data to indexer (#12815)

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

- **Bug Fixes**
- Improved display of image and attachment blocks by ensuring image
captions are shown as content for images, while attachment names remain
as content for attachments.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->


#### PR Dependency Tree


* **PR #12815** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

---------

Co-authored-by: fengmk2 <fengmk2@gmail.com>

packages/backend/server/src/core/utils/__tests__/__snapshots__/blocksute.spec.ts.md

@@ -605,6 +605,7 @@ Generated by [AVA](https://avajs.dev).
             'BFZk3c2ERp-sliRvA7MQ_p3NdkdCLt2Ze0DQ9i21dpA=',
           ],
           blockId: 'lcZphIJe63',
+          content: '',
           docId: 'doc-0',
           flavour: 'affine:image',
           parentBlockId: '6x7ALjUDjj',
@@ -619,6 +620,7 @@ Generated by [AVA](https://avajs.dev).
             'HWvCItS78DzPGbwcuaGcfkpVDUvL98IvH5SIK8-AcL8=',
           ],
           blockId: 'JlgVJdWU12',
+          content: '',
           docId: 'doc-0',
           flavour: 'affine:image',
           parentBlockId: '6x7ALjUDjj',
@@ -633,6 +635,7 @@ Generated by [AVA](https://avajs.dev).
             'ZRKpsBoC88qEMmeiXKXqywfA1rLvWoLa5rpEh9x9Oj0=',
           ],
           blockId: 'lht7AqBqnF',
+          content: '',
           docId: 'doc-0',
           flavour: 'affine:image',
           parentBlockId: '6x7ALjUDjj',
@@ -1236,6 +1239,7 @@ Generated by [AVA](https://avajs.dev).
             'BFZk3c2ERp-sliRvA7MQ_p3NdkdCLt2Ze0DQ9i21dpA=',
           ],
           blockId: 'lcZphIJe63',
+          content: '',
           docId: 'doc-0',
           flavour: 'affine:image',
           parentBlockId: '6x7ALjUDjj',
@@ -1250,6 +1254,7 @@ Generated by [AVA](https://avajs.dev).
             'HWvCItS78DzPGbwcuaGcfkpVDUvL98IvH5SIK8-AcL8=',
           ],
           blockId: 'JlgVJdWU12',
+          content: '',
           docId: 'doc-0',
           flavour: 'affine:image',
           parentBlockId: '6x7ALjUDjj',
@@ -1264,6 +1269,7 @@ Generated by [AVA](https://avajs.dev).
             'ZRKpsBoC88qEMmeiXKXqywfA1rLvWoLa5rpEh9x9Oj0=',
           ],
           blockId: 'lht7AqBqnF',
+          content: '',
           docId: 'doc-0',
           flavour: 'affine:image',
           parentBlockId: '6x7ALjUDjj',