Add the ability to use existingSecrets for Secure Tenancy Chart

[McSick]

Is your feature request related to a problem? Please describe. If you have an existing way to manage secrets, the helm chart will overwrite your secrets.

Describe the solution you'd like Offer optional "existingSecret" config property that will allow you to specify your secrets and not create them in the secrets.yaml.

Describe alternatives you've considered

Additional context

[JamieDanielson]

Just a note for context, this is already being used for the Honeycomb Kubernetes chart, and the request is to use the same sort of logic for Secure Tenancy chart.

[vreynolds]

👋