Fix search block html handling for label and button text

[talldan]

Description

Fixes #38644

The search block was outputting escaped html in its label and button text, when it should have been outputting the tags.

In this PR I've swapped out esc_html for wp_kses.

Testing Instructions

1. Add a search block to a post
2. Use formatting on the label and button text (e.g. bold, italic)
3. Preview the post

Expected - the formatting should be displayed correctly

Screenshots

Before

After

Types of changes

Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).
• I've updated related schemas if appropriate.

[peterwilsoncc]

Minor suggestion re globally allowed attributes.

Any reason you're not using wp_kses_post() and the default set of tags? It saves maintaining a separate allow list if the spec gets more tags.

[peterwilsoncc]

Suggested change

	$wp_kses_formatting_tags = array_map( '_wp_add_global_attributes', $wp_kses_formatting_tags );

Will allow advanced users to add classes, IDs and other pretty safe attributes. See

https://github.com/WordPress/wordpress-develop/blob/f745cc551bb0a54d7df72ec97d23e3359c56048d/src/wp-includes/kses.php#L2559-L2571

[talldan]

I've switched it over to wp_kses_post now, and it looks like it implicitly has the global attributes:
https://github.com/WordPress/wordpress-develop/blob/f745cc551bb0a54d7df72ec97d23e3359c56048d/src/wp-includes/kses.php#L736

Thanks for the advice!

[talldan]

Any reason you're not using wp_kses_post() and the default set of tags? It saves maintaining a separate allow list if the spec gets more tags.

I unashamedly copied the Navigation Link block's code. 😄

It looks like that wasn't the best code to copy. I found this discussion about it - #19477 (comment).

I'll make a separate PR to update any other blocks that might be using wp_kses that could be using wp_kses_post.