This updates breakglass to use the now-upsteamed
https://github.com/gokrazy/breakglass/pull/18 change
so we're not using our fork now.
It also adds a gok wrapper tool, because doing it by hand
was tedious.
Updates #1866
Change-Id: Ifacbf5fbf0e377b3bd95c5f76c18751c2e1af7d7
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
