Allow children of alignfull flow layouts to have root padding.

[tellthemachines]

Trac ticket: https://core.trac.wordpress.org/ticket/61464

Syncs bug fix from WordPress/gutenberg#62670.

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[github-actions]

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Props isabel_brison, aaronrobertshaw.

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[github-actions]

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[aaronrobertshaw]

This tests well for me 👌

The global padding is applied reliably on the frontend for pages, posts, and templates, edited through either the site or post editor. It behaves consistent with WordPress/gutenberg#62670 including with multiple levels of nested group blocks that may or may not apply content width.

[tellthemachines]

committed in r58444.