Look into using OPA cert-controller to manage creation/rotation of SSL certificates

This should ideally be implemented as another certificate source named "builtin" and it should become the default deployment option. The "kubernetes" certificate source should remain though for users who would like to deploy their certificates from something like cert-manager as opposed to having them auto-managed by mimic itself.

Start by reviewing how the existing "kubernetes" certificate source is configured and deployed, then examine OPA cert-controller's creation and rotation behavior. Done means adding a "builtin" certificate source, making it the default deployment option, and retaining "kubernetes" for externally managed certificates.

Written by the indexing model from the issue text.