Use the `qpkg_cli` to check for updates and install them. There are a
couple special things about this compare to other updaters:
* qpkg_cli can tell you when upgrade is available, but not what the
version is
* qpkg_cli --add Tailscale works for new installs, upgrades and
reinstalling existing version; even reinstall of existing version
takes a while
Updates #10178
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>