What?

Closes #69427, #70546
This PR intends to resolve the issue with the block markup being printed on the front, and the missing styles, when the latest posts block is set to display the full post content.

How?

When the option to display the full post content is enabled, use the_content filter to render nested blocks and styles.

Also add a check for the post id, to prevent infinite loops if the post content contains the latest posts block, and prints a "rendering halted" message on the front if debug is enabled.

Using do_blocks() here would also work. I have no strong preference for either, I used the_content because it has been requested by extenders in #70546.

This is basically a copy of what is already used in the post content block, template parts, and patterns
https://github.com/WordPress/gutenberg/blob/trunk/packages/block-library/src/post-content/index.php#L27

Testing Instructions

1. Create a new post and add a Cover block with image and text
2. Create a new post and inset the latest posts block, configured to show full content
3. Create a new page and inset the latest posts block, configured to show full content
4. View the page on the front, confirm that the cover block shows correctly and that there is no block comment printed in the source.
5. If you have WP_DEBUG and WP_DEBUG_DISPLAY enabled, you should see a message saying
   [block rendering halted]

AI assistance: Yes
Tool(s): GitHub Copilot
I told Copilot where to look, it wrote the code and then we discussed the pros and cons of do_blocks() vs the_content().