Add ocserv role

Create a self-signed CA, set up group configs, add script to allow new
connections through the firewall.

In the base debian role, drop the default nftables forward chain with
drop policy because it clashes with this. If you enable forwarding on
a debian host, make sure to configure the firewall.

roles/debian/files/nftables.conf

@@ -23,14 +23,6 @@ table inet filter {
             nd-neighbor-advert, nd-neighbor-solicit, nd-router-advert, nd-router-solicit
         } accept comment "accept IPv6 neighbor discovery"
     }
-
-    chain forward {
-        type filter hook forward priority filter; policy drop
-    }
-
-    chain output {
-        type filter hook output priority filter; policy accept
-    }
 }
 
 include "/etc/nftables.d/*.nft"