Add option to stop connection if SASL authentication fails (irc.server.*.sasl_disconnect_on_fail).

See <https://savannah.nongnu.org/task/?12204>.

This also adds support for the 902 numeric (`ERR_NICKLOCKED`), which is used if SASL authentication fails because an account is frozen, locked or held.
You forgot to update the default values for options (another array below this one).
Please update it as well (otherwise there will be a shift of default values for server options).