I18N: Introduce word_count_type property to WP_Locale.

This changesets adds a `word_count_type` property, so that it does not need to be translated separately across multiple projects.

List of changes:
- New property: `WP_Locale::word_count_type`.
- New method: `WP_Locale::get_word_count_type()`.
- New function: `wp_get_word_count_type()` as a wrapper for `WP_Locale::get_word_count_type()`.
- All `_x( 'words', 'Word count type. Do not translate!' )` strings have been replaced with a call to `wp_get_word_count_type()`.

Props pedromendonca, desrosj, costdev, mukesh27, johnbillion.
Fixes #56698.


git-svn-id: https://develop.svn.wordpress.org/trunk@55279 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/script-loader.php

@@ -1831,12 +1831,7 @@ function wp_just_in_time_script_localization() {
 		'word-count',
 		'wordCountL10n',
 		array(
-			/*
-			 * translators: If your word count is based on single characters (e.g. East Asian characters),
-			 * enter 'characters_excluding_spaces' or 'characters_including_spaces'. Otherwise, enter 'words'.
-			 * Do not translate into your own language.
-			 */
-			'type'       => _x( 'words', 'Word count type. Do not translate!' ),
+			'type'       => wp_get_word_count_type(),
 			'shortcodes' => ! empty( $GLOBALS['shortcode_tags'] ) ? array_keys( $GLOBALS['shortcode_tags'] ) : array(),
 		)
 	);