Privacy: Expose erasure notification recipient to filter callbacks.

The previous `user_email` value was redundant, because it always matched `$request_data->email`. That value might be different from where the message is sent, though, if `the user_erasure_fulfillment_email_to` filter is used. If they are different, then callbacks for the `user_confirmed_action_email_content` filter may want to distinguish between the email address of the user making the request, and the email address that the confirmation notification is being sent to.

Props desrosj, iandunn.
Merges [43236] to the 4.9 branch.
See #43973.
Built from https://develop.svn.wordpress.org/branches/4.9@43237


git-svn-id: http://core.svn.wordpress.org/branches/4.9@43066 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/user.php

@@ -3028,7 +3028,7 @@ function _wp_privacy_send_erasure_fulfillment_notification( $request_id ) {
 
 	$email_data = array(
 		'request'            => $request_data,
-		'user_email'         => $request_data->email,
+		'message_recipient'  => $user_email,
 		'privacy_policy_url' => get_privacy_policy_url(),
 		'sitename'           => get_option( 'blogname' ),
 		'siteurl'            => home_url(),
@@ -3083,7 +3083,9 @@ All at ###SITENAME###
 	 *     Data relating to the account action email.
 	 *
 	 *     @type WP_User_Request $request            User request object.
-	 *     @type string          $user_email         The email address confirming a request.
+	 *     @type string          $message_recipient  The address that the email will be sent to. Defaults
+	 *                                               to the value of `$request->email`, but can be changed
+	 *                                               by the `user_erasure_fulfillment_email_to` filter.
 	 *     @type string          $privacy_policy_url Privacy policy URL.
 	 *     @type string          $sitename           The site name sending the mail.
 	 *     @type string          $siteurl            The site URL sending the mail.

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9.6-beta1-43235';
+$wp_version = '4.9.6-beta1-43237';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.