Enables custom tiered storage for Kafka.

If you want to use custom tiered storage, you must first add a tiered storage for Kafka plugin to the Strimzi image by building a custom container image.

Custom tiered storage configuration enables the use of a custom `RemoteStorageManager` configuration.
`RemoteStorageManager` is a Kafka interface for managing the interaction between Kafka and remote tiered storage.

If custom tiered storage is enabled, Strimzi uses the https://github.com/apache/kafka/blob/trunk/storage/src/main/java/org/apache/kafka/server/log/remote/metadata/storage/TopicBasedRemoteLogMetadataManager.java[`TopicBasedRemoteLogMetadataManager`^] for Remote Log Metadata Management (RLMM).

WARNING: Tiered storage is an early access Kafka feature, which is also available in Strimzi. 
Due to its https://kafka.apache.org/documentation/#tiered_storage_limitation[current limitations^], it is not recommended for production environments.

.Example custom tiered storage configuration
[source,yaml,subs="attributes+"]
----
kafka:
  tieredStorage:
    type: custom
    remoteStorageManager:
      className: com.example.kafka.tiered.storage.s3.S3RemoteStorageManager
      classPath: /opt/kafka/plugins/tiered-storage-s3/*
      config:
        # A map with String keys and String values.
        # Key properties are automatically prefixed with `rsm.config.` 
        # and appended to Kafka broker config.
        storage.bucket.name: my-bucket
  config:
    ...
    # Additional RLMM configuration can be added through the Kafka config 
    # under `spec.kafka.config` using the `rlmm.config.` prefix.
    rlmm.config.remote.log.metadata.topic.replication.factor: 1
----
