conf: Introduce chartcp_tls_x509_cert_dir

conf: Introduce chartcp_tls_x509_cert_dir

Add a new TLS X.509 certificate type - "chardev". This will handle the
creation of a TLS certificate capability (and possibly repository) for
properly configured character device TCP backends.

Unlike the vnc and spice there is no "listen" or "passwd" associated. The
credentials eventually will be handled via a libvirt secret provided to
a specific backend.

Make use of the default verify option as well.

Signed-off-by: John Ferlan <jferlan@redhat.com>