Improve the style of the buttons.

[enricobattocchi]

Context

• The "Copy to a new draft" and "Rewrite & Republish" links in the Block Editor sidebar were displayed as simple underlined text links, which was visually inconsistent with the "Move to trash" button that appears with a bordered button style. This PR updates the styling to provide a more consistent and intuitive user experience.

Summary

This PR can be summarized in the following changelog entry:

• Improves the style of the Copy to a new draft and Rewrite & Republish actions in the Block Editor.

Relevant technical choices:

Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

• Open a published post in the Block Editor
• In the sidebar, under "Status", verify that:
  • "Copy to a new draft" appears as a bordered button (not an underlined link)
  • "Rewrite & Republish" appears as a bordered button (for published posts)

• Verify that clicking the buttons still works correctly (creates a new draft / initiates rewrite & republish)

Relevant test scenarios

• Changes should be tested with the browser console open
• Changes should be tested on different posts/pages/taxonomies/custom post types/custom taxonomies
• Changes should be tested on different editors (Default Block/Gutenberg/Classic/Elementor/other)
• Changes should be tested on different browsers
• Changes should be tested on multisite

The changes are only visible in the Block Editor (Gutenberg). Test on different post types to ensure the buttons appear consistently. Test on different browsers to verify CSS compatibility.

Test instructions for QA when the code is in the RC

• QA should use the same steps as above.

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

UI changes

• This PR changes the UI in the plugin. I have added the 'UI change' label to this PR.

Documentation

• I have written documentation for this change. For example, comments in the Relevant technical choices, comments in the code, documentation on Confluence / shared Google Drive / Yoast developer portal, or other.

Quality assurance

• I have tested this code to the best of my abilities
• I have added unittests to verify the code works as intended

Innovation

• No innovation project is applicable for this PR.
• This PR falls under an innovation project. I have attached the innovation label and noted the work hours.

Fixes #