Tests: Add unit tests for get_next_posts_link() and `get_previous_p…

…osts_link()`.

The tests ensure that the `next_posts_link_attributes` and `previous_posts_link_attributes` filters are applied correctly.

Follow-up to [1383], [5045], [8502], [9632], [55429].

Props geisthanen, mukesh27, costdev, audrasjb, SergeyBiryukov.
Fixes #55751.
Built from https://develop.svn.wordpress.org/trunk@55442


git-svn-id: http://core.svn.wordpress.org/trunk@54975 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.2-beta3-55441';
+$wp_version = '6.2-beta3-55442';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.