Tabs: delay activeId updates until focus can be properly detected

[chad1008]

What?

Make sure the Tabs component doesn't update its internal activeId too early.

Why?

Tabs uses Ariakit internally, which uses an activeId property to track focus internally. In certain situations, it's possible for that internal focus to become out of sync with actual browser focus, so we update it accordingly to ensure arrow key behavior works as expected.

In some cases, such as #56959, the browser focus value doesn't update quickly enough, and our internal syncing efforts lead to arrow keys not working at all, which is obviously not the desired outcome. This PR addresses such cases by delaying the update.

How?

Wrapping our existing logic in requestAnimationFrame() allows enough time to make sure the currently focused ID has finished updating before we check for a mismatch and update our internal focus value.

Testing Instructions

1. First check out Implement Tabs in site-editor settings #56959, as that PR demonstrates the issue we're solving the most clearly.
2. Open a template in the Site Editor
3. Click on the Template tab in the editor setting sidebar
4. Press RightArrow several times. Notice that focus does not move over to the Block tab as it should.
5. Check out this PR, and rebase it off of the branch from the site-editor PR you checked out in a previous step.
6. Refresh the site editor and repeat the test above.
7. Confirm that focus now follows arrow key presses as expected.

[ciampo]

🚀

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Props: shireling, mciampini.

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Co-authored-by: chad1008 <shireling@git.wordpress.org>
Co-authored-by: ciampo <mciampini@git.wordpress.org>

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