ipn/localapi,client/local: add debug watcher for bus events (#16239)

Updates: #15160

Signed-off-by: Claus Lensbøl <claus@tailscale.com>

cmd/tailscaled/tailscaled.go

@@ -719,6 +719,7 @@ func tryEngine(logf logger.Logf, sys *tsd.System, name string) (onlyNetstack boo
 		Dialer:        sys.Dialer.Get(),
 		SetSubsystem:  sys.Set,
 		ControlKnobs:  sys.ControlKnobs(),
+		EventBus:      sys.Bus.Get(),
 		DriveForLocal: driveimpl.NewFileSystemForLocal(logf),
 	}