Helm support for Confluent Kafka setups

[arov00]

The existing helm chart PR sets up cost control for a Strimzi environment. It would be good if we could extend it to also support Kafka clusters that are not deployed using Strimzi. For example, the value file could look as follows:

kafkaType: confluent

# this is not active (and could be omitted) because kafkaType is confluent
strimzi:
  clusterName: my-cluster
  bootstrapServer: my-cluster-kafka-bootstrap:9094
  # more strimzi settings here...

# If confluent is enabled, the chart generates a telegraf config that queries the confluent metrics api + some other confluent-specific things are set up (and strimzi-specific things are deactivated)
confluent:
  bootstrapServer: my-cluster-kafka-bootstrap:9094
  metricsApiSecret:
    name: metrics-api-secret
    apiKeyProperty: key
    apiSecretProperty: secret
  # more confluent settings here...

If Confluent is enabled, then we are no longer able to rely on Strimzi's KafkaConnect and KafkaConnector resources for sinking metrics to timescaleDB. In this case, the setup from Kustomize should be used (spin up a Kafka Connect deployment, instead of using custom resources).