User Story - Card - Counter for every collection

Value proposition

As a user I want to know, how many cards a collection includes. In order to know, how much I have to learn

[ ] the counter counts automatically how many cards my collection includes. Every Collection has his own counter.
[ ] The counter recognizes, when I add or delete a card.

[ ] Create a new State cardCount with useState(cards.legth) at _app.js, so the Counter is managed by parent _app.js
[ ] pass the props vom _app.js to CollectionContainer component.
[ ] connect the cardCount with the function addCard at _app.js with setCardCount(newCards.length)
[ ] connect the cardCount with the function deleteCard at _app.js with setCardcount(cardCount - 1)
[ ] pass cardCount to in the return of _app.js
[ ] return the number of cards in the return-Statement of the CollectionContainer-Component with the cardCount-prop