feat(core): moving in affine-reader doc parsers (#12840)

fix AI-191

#### PR Dependency Tree


* **PR #12840** 👈

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

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

- **New Features**
- Introduced the ability to convert rich text documents into Markdown,
supporting a wide range of content types such as headings, lists,
tables, images, code blocks, attachments, and embedded documents.
- Added support for parsing collaborative document structures and
rendering them as structured Markdown or parsed representations.
- Enhanced handling of database and table blocks, including conversion
to Markdown tables with headers and cell content.

- **Documentation**
  - Added a README noting the use of a forked Markdown converter.

- **Tests**
  - Added new test coverage for document parsing features.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->


#### PR Dependency Tree


* **PR #12840** 👈

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

packages/common/reader/src/reader.ts

@@ -915,3 +915,5 @@ export function readAllDocIdsFromRootDoc(
   }
   return Array.from(docIds);
 }
+
+export { parseBlock, parseBlockToMd, parsePageDoc } from './doc-parser/parser';