Important: #99366 - Add backward compatibility handling for frontend login signing

See forge#99366

Description

The security fix for https://typo3.org/security/advisory/typo3-core-sa-2022-013 enforced the pid HTTP parameter to be signed via HMAC during the frontend user authentication process.

It occurred that custom authentication services suffered from this strict requirements. To provide better backward compatibility for those individual scenarios, the new security.frontend.enforceLoginSigning feature flag has been introduced, which is enabled per default, but can be disabled individually.