Move new user notification emails to add_action() callbacks.

When a new user is created in various places throughout the interface,
notifications are sent to the site admin and the new user. Previously, these
notifications were fired through direct calls to `wp_new_user_notification()`,
making it difficult to stop or modify the messages.

This changeset introduces a number of new action hooks in place of direct calls
to `wp_new_user_notification()`, and hooks the new wrapper function
`wp_send_new_user_notifications()` to these hooks.

Props dshanske, thomaswm, boonebgorges.
Fixes #33587.

git-svn-id: https://develop.svn.wordpress.org/trunk@34251 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/user.php

@@ -176,7 +176,14 @@ function edit_user( $user_id = 0 ) {
 		$user_id = wp_update_user( $user );
 	} else {
 		$user_id = wp_insert_user( $user );
-		wp_new_user_notification( $user_id, null, 'both' );
+		/**
+		  * Fires after a new user has been created.
+		  *
+		  * @since 4.4.0
+		  *
+		  * @param int $user_id ID of the newly created user.
+		  */
+		do_action( 'edit_user_created_user', $user_id );
 	}
 	return $user_id;
 }

src/wp-admin/network/site-new.php

@@ -91,10 +91,18 @@ if ( wp_validate_action( 'add-site' ) ) {
 	if ( !$user_id ) { // Create a new user with a random password
 		$password = wp_generate_password( 12, false );
 		$user_id = wpmu_create_user( $domain, $password, $email );
-		if ( false === $user_id )
+		if ( false === $user_id ) {
 			wp_die( __( 'There was an error creating the user.' ) );
-		else
-			wp_new_user_notification( $user_id, null, 'both' );
+		}
+
+		/**
+		  * Fires after a new user has been created via the network site-new.php page.
+		  *
+		  * @since 4.4.0
+		  *
+		  * @param int $user_id ID of the newly created user.
+		  */
+		do_action( 'network_site_new_created_user', $user_id );
 	}
 
 	$wpdb->hide_errors();

src/wp-admin/network/site-users.php

@@ -77,9 +77,16 @@ if ( $action ) {
 				if ( false === $user_id ) {
 		 			$update = 'err_new_dup';
 				} else {
-					wp_new_user_notification( $user_id, null, 'both' );
 					add_user_to_blog( $id, $user_id, $_POST['new_role'] );
 					$update = 'newuser';
+					/**
+					  * Fires after a user has been created via the network site-users.php page.
+					  *
+					  * @since 4.4.0
+					  *
+					  * @param int $user_id ID of the newly created user.
+					  */
+					do_action( 'network_site_users_created_user', $user_id );
 				}
 			}
 			break;

src/wp-admin/network/user-new.php

@@ -51,7 +51,14 @@ if ( wp_validate_action( 'add-user' ) ) {
 		if ( ! $user_id ) {
 	 		$add_user_errors = new WP_Error( 'add_user_fail', __( 'Cannot add user.' ) );
 		} else {
-			wp_new_user_notification( $user_id, null, 'both' );
+			/**
+			  * Fires after a new user has been created via the network user-new.php page.
+			  *
+			  * @since 4.4.0
+			  *
+			  * @param int $user_id ID of the newly created user.
+			  */
+			do_action( 'network_user_new_created_user', $user_id );
 			wp_redirect( add_query_arg( array('update' => 'added'), 'user-new.php' ) );
 			exit;
 		}