Fix: Hide "Generate Editorial Note" option in Revisions mode

[prasadkarmalkar]

What?

Closes #590

Why?

Currently, when a user opens the Revisions in the block editor, the Generate Editorial Note button is still visible when user clicks any block settings dropdown.

How?

Check the current state of the editor via isPreviewMode of @wordpress/block-editor settings and render the menu item only if its not in preview mode.

Note: We are not able to use isRevisionsMode or showDiff (via isShowingRevisionDiff),. They are registered as private selectors within the @wordpress/editor data store.

Use of AI Tools

AI assistance: Yes
Tool(s): Antigravity
Model(s): Gemini 3.1 Pro
Used for: Identify the core hooks/stores details with implementation of BlockSettingsMenuControls and Create testing instructions in PR.

Testing Instructions

1. Navigate to Settings → AI and ensure AI Editorial Notes is enabled.
2. Create or edit a post and add some paragraph blocks.
3. Save the post, make a change, and save it again to generate a revision history.
4. Open the post settings sidebar and click to view Revisions.
5. Inside the Revisions diff viewer, click on any block to open its block settings menu (the 3 dots).
6. Verify that "Generate Editorial Note" does not appear in the menu (only Copy and Copy Styles should be visible).
7. Exit the Revisions view and return to the normal editor.
8. Click on a block to open its block settings menu, and verify that "Generate Editorial Note" does appear normally.

Screenshots or screencast

Before	After

Changelog Entry

Fixed - "Generate Editorial Note" button appearing in the block settings menu during post revisions.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.06%. Comparing base (7fafa86) to head (d13953d).

Additional details and impacted files

@@            Coverage Diff             @@
##             develop     #591   +/-   ##
==========================================
  Coverage      73.06%   73.06%           
  Complexity      1731     1731           
==========================================
  Files             85       85           
  Lines           7466     7466           
==========================================
  Hits            5455     5455           
  Misses          2011     2011           

Flag	Coverage Δ
unit	73.06% <ø> (ø)

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[github-actions]

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Co-authored-by: prasadkarmalkar <prasadkarmalkar@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>

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