Enable inline comments on published post

[karthick-murugan]

What?

Closes #71245

This PR restores the ability to add block-level comments on published posts. Previously, the functionality was removed in #66583, but this update ensures that users can continue to add comments even after a post has been published.

Why?

There are many use cases where published posts still receive updates or collaborative changes. Without this fix, users cannot add block-level comments once a post is published, which limits collaboration and feedback opportunities.
This PR makes block commenting consistent across draft and published states.

Testing Instructions

1. Enable the block-level commenting experiment via
   wp-admin/admin.php?page=gutenberg-experiments.
2. Create a new draft.
3. Add block comments to one or more blocks.
4. Publish the post.
5. Verify that new comments can still be added to blocks on the published post.

Testing Instructions for Keyboard

1. Navigate to a published post using only the keyboard.
2. Focus on a block that already has comments.
3. Confirm that it is possible to add a new block comment via keyboard navigation (no reliance on mouse).

Screenshots or screencast

[github-actions]

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Co-authored-by: karthick-murugan <[email protected]>
Co-authored-by: adamsilverstein <[email protected]>
Co-authored-by: Mamaduka <[email protected]>
Co-authored-by: joemcgill <[email protected]>

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[adamsilverstein]

Looks good!

[adamsilverstein]

@t-hamano does this look ok to you? Do you have any context for why commenting was disabled for published posts previously?

[Mamaduka]

We can merge this. IIRC, the condition was temporary.

P.S. Rebasing should restart stalled tests.

[karthick-murugan]

We can merge this. IIRC, the condition was temporary.

P.S. Rebasing should restart stalled tests.

Rebased.

[t-hamano]

Sorry for the comment after the PR has been merged.

This PR unintentionally exposed the block commenting to the template or template parts editor. I think we'll need to somehow disable block comments for any screens or post types where they don't work. See #66377 (comment) for more details.

[Mamaduka]

Maybe support for block comments should be declared on the Post Type level.