Composer: Add `simplesamlphp/simplesamlphp` for ILIAS 12

[fhelfer]

This PR suggests adding simplesamlphp/simplesamlphp (v. 2.4.3) as composer dependency.

General Information:

• [X] this dependency was already used in ILIAS.
• [X] License: LGPL-2.1

Usage:

• components/ILIAS/Saml

Wrapped By:

• \ilSimpleSAMLphpWrapper (implements \ilSamlAuth)
• \ilSimpleSAMLphplIdpDiscovery (implements \ilSamlIdpDiscovery)
• \ILIAS\Saml\DefaultSimpleSamlFactory (implements \ILIAS\Saml\SimpleSamlFactory)
• \ILIAS\Saml\Module
• \ILIAS\Saml\Metadata

Reasoning:

• SimpleSAMLphp is an award-winning application written in native PHP that deals with secure authentication. The main focus of SimpleSAMLphp is providing support for SAML 2.0 as both "Service Provider" and "Identity Provider".
• SAML is a very complex standard (in my personal opinion, see https://datatracker.ietf.org/doc/html/rfc7522 and linked documents) and we should not try to/do not want to reinvent the wheel in ILIAS. So we should rely on this library crafted by these authentication/security standard specialists.

Maintenance:

• SimpleSAMLphp is actively maintained by multiple contributors (see: https://simplesamlphp.org/contrib/). There is recent activity (even this week, see: https://github.com/simplesamlphp/simplesamlphp/commits/master).
• Security issues are always fixed in a timely manner followed by new releases. A proper security process is implemented: https://simplesamlphp.org/security/ .

Links:

• Packagist: https://packagist.org/packages/simplesamlphp/simplesamlphp
• GitHub: https://github.com/simplesamlphp/simplesamlphp
• Documentation: https://simplesamlphp.org/docs/

[matthiaskunkel]

Jour Fixe, 08 DEC 2025: Dependency is accepted for ILIAS 12.