Backport: Block Styles: Allow registration of block styles across block types and include style data

[aaronrobertshaw]

Adds to core the functionality from:

• Block Styles: Add extended version of register block style functions gutenberg#61029

The Gutenberg PR linked above was forced to add a new global function because the core WP_Block_Styles_Registry class was marked as final. This backport involves updating the WP_Block_Styles_Registry class directly with matching functionality.

Included is the addition of style_data within the supported style properties. The style_data property is a theme.json shaped array that will be used by the new section styling feature to generate a dynamic stylesheet for the block style.

Trac ticket: https://core.trac.wordpress.org/ticket/61274

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[talldan]

Changes look good to me, thanks for adding tests

[tellthemachines]

Changes LGTM and testing locally with the instructions from WordPress/gutenberg#61029 works as expected!

[tellthemachines]

Committed in r58246.