Categories: Add color block support

[carolinan]

What?

Adds text, background, gradient, and link color support to the categories (Categories list) block.
Background, text and link are set to show by default.

Partial for #43245

Why?

The block is missing these options. Adding them improves the consistency and enables more design options.

How?

The PR updates the block supports in block.json, and the documentation.

Testing Instructions

Add some categories.
Create a new post and add the categories list block. Adjust the color settings and compare the result in the editor and front.
Next test the global styles options from the Styles sidebar in the Site Editor.

Screenshots or screencast

[github-actions]

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

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