Update to Twemoji 16 for Emoji 16 support

[peterwilsoncc]

Updates to Emoji 16:

• Introduces a new test to account for single data point emoji tests, emojiRendersEmptyCenterPoint
• Updates the flag test from UN to Sark (CQ) 🇨🇶
• Adds a test for an Emoji 16 emoji, Shovel 🪏 Splatter 🫟
• Modesty aside, uses a pretty good pun in the comments
• Updates the CDN URL to point to the 16.0.1 images.
• Updates the grunt script to pull emoji images from the 16.0.1 version of Twemoji for generating the regex
• Updates Twemoji (regex only change)
• I'm leaving the bot to update the formatting.php regex.

@westonruter Would you be able to validate that I am passing the new function around correctly for the support tests to continue working in workers?

@pento I based the test for an empty center point on the tests in the version in the 4.2 branch, do you recall if that caused any problems?

wordpress-develop/src/wp-includes/js/wp-emoji-loader.js

Lines 42 to 48 in d3c5f3a

	/*
	* This creates a smiling emoji, and checks to see if there is any image data in the
	* center pixel. In browsers that don't support emoji, the character will be rendered
	* as an empty square, so the center pixel will be blank.
	*/
	context.fillText( String.fromCharCode( 55357, 56835 ), 0, 0 );
	return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;

Trac ticket: https://core.trac.wordpress.org/ticket/63324

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[pento]

I based the test for an empty center point on the tests in the version in the 4.2 branch, do you recall if that caused any problems?

This would potentially cause the test to incorrectly fail if the site or UA is using Noto Emoji Font, as it looks like the centre pixel for the shovel would be white. This is an extreme edge case that I usually wouldn't be concerned about, particularly as it hasn't caused any reported issues with the historical smiley used.

If you feel like addressing it, it could probably be mitigated by testing with the splatter emoji, instead.

[westonruter]

Would you be able to validate that I am passing the new function around correctly for the support tests to continue working in workers?

@peterwilsoncc This looks good to me!