[MOOSE-408] Dedupe class tokens in getBaseClassName to avoid duplicated classes

[spadilha]

What does this do/fix?

This pull request fixes an issue in the create-wp-controls.js utility where CSS classes were being duplicated in the output of getBaseClassName when propsClassName already included attributeClassName or attributeClasses. The logic now deduplicates class tokens across all three sources to prevent redundant classes.

Bug fix:

• Updated getBaseClassName in create-wp-controls.js to deduplicate class name tokens across propsClassName, attributeClassName, and attributeClasses, ensuring no duplicate classes are output.
• Documented the fix in the CHANGELOG.md under version 2026.07, referencing MOOSE-408.

Note: on the live front-end this is largely masked because WordPress's server-side layout support re-serializes the class attribute via WP_HTML_Tag_Processor (which treats classes as a set), but the duplication is still present in stored post_content.

QA

Links to relevant issues

• Link to Issue

Pull request checklist

• I've added a changelog entry for these changes.
• I've linked to a relevant Jira issue.

[Copilot]

Pull request overview

This pull request fixes duplicated CSS classes produced by getBaseClassName in the block controls utility by deduplicating class tokens across multiple class sources, and documents the fix in the changelog.

Changes:

• Deduplicate class name tokens across propsClassName, attributeClassName, and attributeClasses in getBaseClassName.
• Add a 2026.07 changelog entry referencing MOOSE-408.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
wp-content/themes/core/assets/js/utils/create-wp-controls.js	Updates getBaseClassName to split into tokens and dedupe via Set before returning the merged class string.
CHANGELOG.md	Documents the fix under the new 2026.07 entry with a link to MOOSE-408.

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