m/n/core/network: implement LLDP transmission

Implements simple LLDP transmission-only support for Monogon OS. It
advertises enough to do topology discovery through LLDP. Currently it
supports MAC address, interface name, node name and product
name/version. More information can be added in the future.

Tested using Wireshark on launch-cluster node/switch traffic.

Change-Id: If5777bc042ef87bd8d26c548324c6de6f14f7270
Reviewed-on: https://review.monogon.dev/c/monogon/+/4282
Tested-by: Jenkins CI
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
diff --git a/go.mod b/go.mod
index 99ef13e..9b49723 100644
--- a/go.mod
+++ b/go.mod
@@ -89,6 +89,7 @@
 	github.com/mdlayher/ethtool v0.2.0
 	github.com/mdlayher/genetlink v1.3.2
 	github.com/mdlayher/kobject v0.0.0-20200520190114-19ca17470d7d
+	github.com/mdlayher/lldp v0.0.0-20150915211757-afd9f83164c5
 	github.com/mdlayher/netlink v1.7.3-0.20250113171957-fbb4dce95f42
 	github.com/mdlayher/packet v1.1.2
 	github.com/miekg/dns v1.1.58