"The WALLOPS command is used to send a message to all currently connected
users who have set the 'w' user mode for themselves."
-- https://datatracker.ietf.org/doc/html/rfc2812#section-4.7
-- https://github.com/ircdocs/modern-irc/pull/118
"Servers MAY echo WALLOPS messages to their sender even if they don't have
the 'w' user mode.
Servers MAY send WALLOPS only to operators."
-- https://github.com/ircdocs/modern-irc/pull/118