Update sshd_config (#13143)

Afaik, adding these lines does nothing unless the file(s) are present. Having them in let's admins supply certs instead of relying on TOFU.

Co-authored-by: zeripath <art27@cantab.net>

docker/root/etc/templates/sshd_config

@@ -8,9 +8,13 @@ ListenAddress ::
 LogLevel INFO
 
 HostKey /data/ssh/ssh_host_ed25519_key
+HostCertificate /data/ssh/ssh_host_ed25519_cert
 HostKey /data/ssh/ssh_host_rsa_key
+HostCertificate /data/ssh/ssh_host_rsa_cert
 HostKey /data/ssh/ssh_host_ecdsa_key
+HostCertificate /data/ssh/ssh_host_ecdsa_cert
 HostKey /data/ssh/ssh_host_dsa_key
+HostCertificate /data/ssh/ssh_host_dsa_cert
 
 AuthorizedKeysFile .ssh/authorized_keys
 AuthorizedPrincipalsFile .ssh/authorized_principals