LDAP protocol/host/port configuration by URL; make BASE_DN optional

PHP ldap_connect($host, $port) function signature is deprecated: https://www.php.net/manual/en/function.ldap-connect.php

Querying an AD Global Catalog across an entire forest requires an empty base DN

config.default.php

@@ -102,12 +102,9 @@ define('DB_TIMEOUT', null);
 // Enable LDAP authentication (false by default)
 define('LDAP_AUTH', false);
 
-// LDAP server hostname
+// LDAP server protocol, hostname and port URL (ldap[s]://hostname:port)
 define('LDAP_SERVER', '');
 
-// LDAP server port (389 by default)
-define('LDAP_PORT', 389);
-
 // By default, require certificate to be verified for ldaps:// style URL. Set to false to skip the verification
 define('LDAP_SSL_VERIFY', true);