Enabe a secure way for setting up secrets in cruisecontrol.properties file

[play-io]

Is your feature request related to a problem? Please describe.

• Cruise Control can post self-healing and anomaly detection events to a Slack channel.
• Connection details for Slack must be provided in cruisecontrol.properties ex slack.self.healing.notifier.webhook property.
• Slack's webhook is a secret and should not be presented in clear text ex in a GIT repository.
• Koperator assumes cruisecontrol.properties properties defined in KafkaCluster custom resource and therefore value of slack.self.healing.notifier.webhook should be there as well.
• Because I don't want keep clear text value in slack.self.healing.notifier.webhook I was looking for a way ex:
• • refer to a value from a Secret
• • or refer to a value from ENV variable
    but cannot see it's possible now.

Describe the solution you'd like to see
Introduce syntax/[substitution variables] which can be used in ex KafkaCluster CR and be translated by "engine" (operator??) to values from a Secret or env variables.

Describe alternatives you've considered
N/A

Additional context
N/A

[panyuenlau]

Hey @play-io, thanks for you feature request! Did you get to join our Slack channel where we can better felicitate discussion like this?

[play-io]

Hey @play-io, thanks for you feature request! Did you get to join our Slack channel where we can better felicitate discussion like this?

Will do. Thanks!