Categories List: Add border block support

[akasunil]

What?

Add border block support to the Categories List block.

Part of #43247

Why?

Categories List block is missing border support.

How?

Adds the border block support in block.json

Testing Instructions

• Go to Global Styles setting ( under appearance > editor > styles > edit styles > blocks )
• Make sure that Categories List block's border is configurable via Global Styles
• Verify that Global Styles are applied correctly in the editor and frontend
• Edit template/page, Add Categories List block and Apply the border styles
• Verify that block styles take precedence over global styles
• Verify that block borders display correctly in both the editor and frontend

Watch attached video for more information.

Screenshots or screencast

Blog-Home-.-Template-.-gutenberg-.-Editor-.-WordPress.9.webm

[github-actions]

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Co-authored-by: akasunil <sunil25393@git.wordpress.org>
Co-authored-by: carolinan <poena@git.wordpress.org>

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[carolinan]

I have followed the testing instructions and the border is working as described.

When there is only one category in the list, the content is slightly offset because the list item has a bottom margin of 0.5rem. Then the content is not perfectly vertically centered inside the border. But I don't think that should block this PR.

[akasunil]

Thank you @carolinan

the content is slightly offset because the list item has a bottom margin of 0.5rem. Then the content is not perfectly vertically centered inside the border.

Spent little time on this, it appears to be theme-specific. When I tested it with an empty theme, the categories list had no margin.