[karma] Allow passing private CA from a ConfigMap

[aslafy-z]

Most of the time, certificate authorities can be stored in ConfigMap as the certificate on itself is not a sensitive information.
In my setup, the company CA is synced in all the user namespaces, in a configmap resource. I'd like to use this configmap instead of having to create some specific secret for Karma.

See
https://github.com/wiremind/wiremind-helm-charts/blob/main/charts/karma/values.yaml#L178-L184
https://github.com/wiremind/wiremind-helm-charts/blob/main/charts/karma/templates/deployment.yaml#L131-L136

[maximee-leroyy]

Hi, PRs are welcome!