We can't rely on a frontend to provide a control
server URL, so this naturally belongs in server-persisted
state.
Signed-off-by: David Anderson <dave@natulte.net>
This is a prelude to supporting relaynode's --routes in
tailscaled. The daemon needs to remembers routes to
advertise, and the CLI needs to be able to change the
set of advertised routes. Prefs is the thing used for
both of these.
Signed-off-by: David Anderson <dave@natulte.net>
