client: allow the expiry time to be specified for new keys

Adds a parameter for create key that allows a number of seconds
(less than 90) to be specified for new keys.

Fixes https://github.com/tailscale/tailscale/issues/7965

Signed-off-by: Matthew Brown <matthew@bargrove.com>

cmd/get-authkey/main.go

@@ -67,7 +67,7 @@ func main() {
 		},
 	}
 
-	authkey, _, err := tsClient.CreateKey(ctx, caps)
+	authkey, _, err := tsClient.CreateKey(ctx, caps, 0)
 	if err != nil {
 		log.Fatal(err.Error())
 	}