Implement LdapRule to limit user logins by objectclass.

Now logins are allowed by any objectclass unless LDAP_LOGIN_OBJECTCLASS is defined, we should be an array of allowed objectClass (any match).
Improvement for #245

app/Ldap/Rules/LoginObjectclassRule.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace App\Ldap\Rules;
+
+use Illuminate\Database\Eloquent\Model as Eloquent;
+use LdapRecord\Laravel\Auth\Rule;
+use LdapRecord\Models\Model as LdapRecord;
+
+/**
+ * User must have this objectClass to login
+ *
+ * This is overridden by LDAP_LOGIN_OBJECTCLASS
+ * @see User::$objectClasses
+ */
+class LoginObjectclassRule implements Rule
+{
+    public function passes(LdapRecord $user, Eloquent $model = null): bool
+    {
+		if ($x=config('ldap.login.objectclass')) {
+			return count(array_intersect($user->objectclass,$x));
+
+		// Otherwise allow the user to login
+		} else {
+			return TRUE;
+		}
+    }
+}