The new read-only mode is only accessible when running `tailscale web`
by passing a new `-readonly` flag. This new mode is identical to the
existing login mode with two exceptions:
- the management client in tailscaled is not started (though if it is
already running, it is left alone)
- the client does not prompt the user to login or switch to the
management client. Instead, a message is shown instructing the user
to use other means to manage the device.
Updates #10979
Signed-off-by: Will Norris <will@tailscale.com>
Will Norris
128c99d4ae