control/controlclient, localapi: shorten expiry time via localapi (#4112)

Signed-off-by: Nick O'Neill <nick@tailscale.com>

control/controlclient/client.go

@@ -11,6 +11,7 @@ package controlclient
 
 import (
 	"context"
+	"time"
 
 	"tailscale.com/tailcfg"
 )
@@ -45,6 +46,9 @@ type Client interface {
 	// Logout starts a synchronous logout process. It doesn't return
 	// until the logout operation has been completed.
 	Logout(context.Context) error
+	// SetExpirySooner sets the node's expiry time via the controlclient,
+	// as long as it's shorter than the current expiry time.
+	SetExpirySooner(context.Context, time.Time) error
 	// SetPaused pauses or unpauses the controlclient activity as much
 	// as possible, without losing its internal state, to minimize
 	// unnecessary network activity.