IDS: Allow to inspect traffic from or to OpenVPN

IDS: Allow to inspect traffic from or to OpenVPN

This commit allows to configure suricata to monitor traffic from or to
OpenVPN tunnels. This includes the RW server and all established N2N
connections.

Because the RW server and/or each N2N connection uses it's own tun?
device, it is only possible to enable monitoring all of them or to disable
monitoring entirely.

Fixes #12111.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>