Adds the eventbus to the router subsystem. The event is currently only used on linux. Also includes facilities to inject events into the bus. Updates #15160 Signed-off-by: Claus Lensbøl <claus@tailscale.com>
Updates #5794 Change-Id: Ib78a3ea971a2374d405b024ab88658ec34be59a6 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>