Emoji: Bring Twemoji compatibility to PHP.

This was previously attempted in [41043], which unfortunately had severe performance issues, the regex it used was fatally slow on long posts.

This version now uses an array of all emoji that Twemoji supports, which maintains the accuracy of [41043], while being the same speed or only a few ms slower than the code prior to [41043].

As with [41043], the `grunt precommit:emoji` task detects when `twemoji.js` has changed, and regenerates the array.

Props jmdodd for feedback, suggestions, and insults where appropriate.
Fixes #35293. 🤞🏻


Built from https://develop.svn.wordpress.org/trunk@41701


git-svn-id: http://core.svn.wordpress.org/trunk@41535 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41700';
+$wp_version = '4.9-alpha-41701';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.