feat: One side TLS for Kafka

[RafalSkolasinski]

Building on top of #4658
Closes #4870

Tested with:

• Strimzi Plain
• Strimzi one sided TLS
• Strimzi mTLS
• Confluent Cloud

To make use of one -sided TLS simply leave security.kafka.ssl.client.secret value unset, e.g.

kafka:
  bootstrap: seldon-kafka-tls-bootstrap.kafka:9093

security:
  kafka:
    protocol: SSL
    ssl:
      client:
        secret:
        brokerValidationSecret: kafka-broker-auth
        endpointIdentificationAlgorithm: https

Note: this also adds propagation of

security:
  kafka:
    ssl:
      client:
        endpointIdentificationAlgorithm: https

Helm value to Golang client if SSL or SASL_SSL is being used.
Empty value will result in none value being set as otherwise golang client raises

Configuration property "ssl.endpoint.identification.algorithm" cannot be set to empty value.

[RafalSkolasinski]

For reference, strimzi listeners configuration for testing:

    listeners:
    - name: plain
      port: 9092
      tls: false
      type: loadbalancer
    - name: tls
      port: 9093
      tls: true
      type: loadbalancer
    - authentication:
        type: tls
      name: mtls
      port: 9094
      tls: true
      type: loadbalancer

values for plain test:

kafka:
  bootstrap: seldon-kafka-plain-bootstrap.kafka:9092

security:
  kafka:
    protocol: PLAINTEXT

values for one sided TLS test

kafka:
  bootstrap: seldon-kafka-tls-bootstrap.kafka:9093

security:
  kafka:
    protocol: SSL
    ssl:
      client:
        brokerValidationSecret: kafka-broker-auth

values for mTLS test

kafka:
  bootstrap: seldon-kafka-mtls-bootstrap.kafka:9094

security:
  kafka:
    protocol: SSL
    ssl:
      client:
        secret: kafka-client-auth
        brokerValidationSecret: kafka-broker-auth
        endpointIdentificationAlgorithm:

values for confluent cloud kafka test

kafka:
  bootstrap: <bootstrap servers URI>
  topics:
    replicationFactor: 3
  consumer:
    messageMaxBytes: 8388608
  producer:
    messageMaxBytes: 8388608

security:
  kafka:
    protocol: SASL_SSL
    sasl:
      mechanism: "PLAIN"
      client:
        username: <user name here>
        secret: confluent-kafka-secret
    ssl:
      client:
        secret: kafka-client-auth
        brokerValidationSecret: kafka-broker-auth
        endpointIdentificationAlgorithm: https

[SDJustus]

works as expected. Thank you very much! 💯