Supply client cert for API calls to mTLS enabled Solr clusters

[thelabdude]

If the Solr cluster requires mTLS, then the http.Client used by api.go needs to supply a client cert and optionally the Certificate Authority (CA) cert if not already trusted between client & server. This means adding the following config to the http.Transport object for the http.Client:

				TLSClientConfig: &tls.Config{
					ClientCAs:          caCertPool,
					Certificates:       []tls.Certificate{clientCert},
                                          ...
				},

The server(s) will need to be configured to trust the CA that issued the client cert.

[HoustonPutman]

Is this something that we need to setup with the solr-operator pod, or can it be done dynamically?