unread comment icon in card disappears only after page reload

[jakobroehrl]

it should disappear after opening the cardsidebar and the commends tab

[jakobroehrl]

@juliushaertl
How to do this best?
Trigger this every x secons? https://github.com/nextcloud/deck/blob/master/src/components/cards/CardBadges.vue#L60-L62
Like we are doing it here: https://github.com/nextcloud/deck/blob/master/src/components/card/CardSidebar.vue#L339-L340