HTTP API: Adds BC-layer /library/Requests.php file.

When the Requests 2.0.0 [https://github.com/WordPress/Requests/blob/7ef0774f0bf32dddb7b6c1dd01e4d285c2ba3c3f/src/Autoload.php#L141-L143 autoloader detects the older (deprecated) `Requests` class], it attempts to load [https://github.com/WordPress/Requests/blob/v2.0.0/library/Requests.php its `/library/Requests.php` file]. Prior to this commit, this file did not exist in Core. Thus, a fatal error happened.

Why not change Requests Autoloader?
Requests is an external dependency that Core consumes. It is also used by other projects outside of Core. Thus, Core needs a fix to guard itself to prevent a fatal error.

The fix:
* Adds the missing `wp-includes/Requests/library/Requests.php` file, which then loads the `wp-includes/class-requests.php` (which will throw a deprecation notice to alert developers to upgrade).
* Adds a test.

Follow-up to [54997].

Props bjorsch, costdev, jrf, mukesh27, peterwilsoncc, ironprogrammer, hellofromTonya.
Fixes #57341.
Built from https://develop.svn.wordpress.org/trunk@55007


git-svn-id: http://core.svn.wordpress.org/trunk@54540 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/Requests/library/Requests.php

@@ -0,0 +1,12 @@
+<?php
+/**
+ * Loads the old Requests class file when the autoloader
+ * references the original PSR-0 Requests class.
+ *
+ * @deprecated 6.2.0
+ * @package WordPress
+ * @subpackage Requests
+ * @since 6.2.0
+ */
+
+include_once ABSPATH . WPINC . '/class-requests.php';

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.2-alpha-55006';
+$wp_version = '6.2-alpha-55007';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.