Updates tailscale/corp#17859
Provides a local API endpoint to be called from the GUI to inform the backend when the client menu is opened or closed.
cc @bradfitz
Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
Signed-off-by: Andrea Gottardo <andrea@tailscale.com>
Signed-off-by: Andrea Gottardo <andrea@gottardo.me>