Login and Registration: Add /login.php as an alias for the login page.

This aims to make the login process more user-friendly.

Follow-up to [19875], [19880].

Props lancewillett, subrataemfluence, tejwanihemant, ankit-k-gupta, devmuhib, audrasjb, hellofromTonya, joemcgill.
Fixes #40762.

git-svn-id: https://develop.svn.wordpress.org/trunk@56718 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-includes/canonical.php

@@ -1028,6 +1028,7 @@ function wp_redirect_admin_locations() {
 
 	$logins = array(
 		home_url( 'wp-login.php', 'relative' ),
+		home_url( 'login.php', 'relative' ),
 		home_url( 'login', 'relative' ),
 		site_url( 'login', 'relative' ),
 	);