What?

Closes: #70065

The PR handles the presence of both markdown and block markup when pasting.

Why?

Currently, when content containing both Markdown and block markup is pasted, it doesn’t parse as expected.
Example

```
<!-- wp:pattern {"slug":"twentytwentyfive/header"} /-->

```

The block markup inside the fenced code block is incorrectly rendered as content, rather than being treated as code.

How?

The pasted content is now passed through a Markdown-to-HTML converter before block parsing begins. Additionally, After parsing any classic content is converted to blocks using the rawHandler.
This allows mixed content to be parsed correctly. For instance:

<!-- wp:pattern {"slug":"twentytwentyfive/header"} /-->
# Some heading
```
<!-- wp:pattern {"slug":"twentytwentyfive/header"} /-->
```

Testing Instructions

1. Open a post
2. Paste content containing a mix of Markdown and block markup to match format (cmd/ctrl + shift + v). Example:

<!-- wp:pattern {"slug":"twentytwentyfive/header"} /-->
# Some heading
```
<!-- wp:pattern {"slug":"twentytwentyfive/header"} /-->
```

3. Confirm that:

• The block markup outside the code block is parsed into blocks.
• The block markup inside the fenced code block is preserved as code and not parsed as a block.

Testing Instructions for Keyboard

Screenshots or screencast

Before	After