New Feature: Messenger: Multiple Failure Transports Transports

closes #15168

This PR adds the documentation related to PR: symfony/symfony#38468

What it needs to be clear in the documentation:

• You can define multiple transports, one per transport (instead of the global one, as it is supported today)
• If you don't define a global failure transport and if the transport does not have the failure_transport configured the messages will be discarded
• If you define both a global and at the transport level, the failure_transport configuration, the one taken into account is at the transport level configuration.
• The failed commands have an option argument to specify the transport level --transport. Without arguments is the global failed transport taken into account.