Canonical: Add $x_redirect_by parameter to wp_redirect() that allows applications doing the redirect to identify themselves.

This complements the `x_redirect_by` filter added in [42408].

Props NathanAtmoz, johnbillion.
Fixes #42313.

git-svn-id: https://develop.svn.wordpress.org/trunk@42633 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/pluggable.php

@@ -176,7 +176,8 @@ class Tests_Pluggable extends WP_UnitTestCase {
 			),
 			'wp_redirect'                     => array(
 				'location',
-				'status' => 302,
+				'status'        => 302,
+				'x_redirect_by' => 'WordPress',
 			),
 			'wp_sanitize_redirect'            => array( 'location' ),
 			'_wp_sanitize_utf8_in_redirect'   => array( 'matches' ),