The SQL CLI was being a bit cavalier about `null`, `ctrl-c`, and
`ctrl-d` while reading passwords to the point where it'd halt with
an exception if the user hit `ctrl-d` while typing a password. This
changes it so that the CLI will instead shut down if the user
`ctrl-c`s or `ctrl-d`s while on the password prompt with an
ENOPERM error code.
This also fixes a packaging test failure I caused by a copy and paste
error where the CLI was always enforcing things as though it was reading
a password all the time. This error was causing packaging test failures.
Original commit: elastic/x-pack-elasticsearch@a882c50fc7
47a2f63d5e