Projectors send too many messages to mercure

This is code from the ScoreBoardProjector:

    public function __invoke(Event $event): void
    {
        parent::__invoke($event);

        if ($event instanceof TableAwareEvent) {
            $this->notifier->notify(
                new ScoreLogUpdateNotification($event->getTableIdentifier()),
            );

            return;
        }

        // I wish I had provided a TableIdentifier in every event this projector listens to.
        if ($event instanceof SheetAffectingEvent) {
            $tableIdentifier = $this->tablesBySheet->getTableByScoreSheet(
                $event->getScoreSheetIdentifier()
            );
            $this->notifier->notify(
                new ScoreLogUpdateNotification($tableIdentifier),
            );
        }
    }

This sends a notification to the notifier on every TableAwareEvent and every SheetAffectingEvent, even if the projector doesn't do anything with the event. We should emit a notification in the concrete handler methods, and only if something has effectively changed.

This should be fixed in every notifying projector.