desktop-goodies: irssi: handle no args

Do not attempt to change window classname if window id is not supplied.

Signed-off-by: Aliaksei Katovich <aliaksei.katovich@gmail.com>
desktop-goodies: irssi: pass window id arg

Pass window id to irssi-notify-show so window classname can be changed.

Signed-off-by: Aliaksei Katovich <aliaksei.katovich@gmail.com>