Add capability from rfc8950.

Just the basic parser, still needs to be integrated into the rest of the
code for the OPEN message parsing, and then the rest of the MP
Reach/Unreach NLRI parsing needs to be added.

bgpd/src/route_client/main.rs

@@ -13,7 +13,6 @@
 // limitations under the License.
 
 use bgpd::route_client::netlink::NetlinkConnector;
-use bgpd::route_client::southbound_interface::DummyVerifier;
 use bgpd::route_client::southbound_interface::SouthboundInterface;
 use clap::Parser;
 use log::trace;