Add preview example for comments-count and comments-link

[Infinite-Null]

Part of #64707

What?

This PR adds example attributes to the Post Comments Count and Post Comments Link blocks to provide block previews in the inserter with optimized viewport width.

Testing Instructions

1. Open a post or page in the WordPress block editor.
2. Open the block inserter by clicking the "+" button.
3. Search for "Post Comments Count" and "Post Comments Link" blocks in the inserter.
4. Hover over these blocks in the inserter to see the previews with the new viewport width setting.

Screenshots

Before	After

While working on this issue, I noticed a minor warning that appears briefly on reload:
Post Comments Link block: post not found.

This is not issue for preview example but as per my understanding it is related to the fact that this:

const hasPostAndComments = postId && commentsCount !== undefined;

takes a moment to load. As a result, the warning gets triggered by the code at the following locations:

gutenberg/packages/block-library/src/post-comments-link/edit.js

Line 104 in 94af11b

{ __( 'Post Comments Link block: post not found.' ) }

gutenberg/packages/block-library/src/post-comments-count/edit.js

Line 75 in 94af11b

{ __( 'Post Comments Count block: post not found.' ) }

Screencast:

Screen.Recording.2025-08-01.at.4.34.13.PM.mov

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Co-authored-by: Infinite-Null <ankitkumarshah@git.wordpress.org>
Co-authored-by: yogeshbhutkar <yogeshbhutkar@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>

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[yogeshbhutkar]

LGTM 👍

Edit: As this is my first time, I’d like to wait for a second review to confirm everything is in order before proceeding with a merge.

[yogeshbhutkar]

While working on this issue, I noticed a minor warning that appears briefly on reload.

The current behaviour occurs because the value is set asynchronously following an apiFetch call. This results in a warning being shown before the data loads.

Ref:

gutenberg/packages/block-library/src/post-comments-count/edit.js

Line 39 in a9e3fda

apiFetch( {

Typically, other blocks display a reasonable default while fetching data; for instance, the post-author-name block shows “Author Name” during loading.

Ref:

gutenberg/packages/block-library/src/post-author-name/edit.js

Line 59 in a9e3fda

const displayName = authorName?.name || __( 'Author Name' );

This can be addressed separately as a follow-up, so it doesn’t need to block this PR.

I'll be requesting a confidence review to move this PR forward.

[Mamaduka]

Looks good! Thanks, @Infinite-Null!