logger: add env var to duplicate all logs to stdout (#9618)
logger: add env var to duplicate all logs to stdout (#9618)

This is useful when debugging freezes/timeouts, so we can see the log
without having to wait until the test completes.

Suggested by jzila.
keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client