It should be noted there is a circular dependency with mTLS authentication; in order to fetch a certificate we need
a certificate. This can be handled in various ways:
* `GenerateSecret` may additionally write any signed certificates to disk, with `OUTPUT_CERTS` configured.
* Users may have external CA setups that pre-configure certificates.
* The CaClient can use JWT token for the initial setup, then switch to mTLS certificates.