Draft: Card and CardsGridView rework

This MR aims to improve and fix Card and CardsGridView. How it works in the background and add extra features (e.g. alignment option, card height, banner margin). These are some of my goals that myself already poorly implemented in testing branch a long time ago. This is going to take quite some time to get done properly and will probably be done next month.

This is meant for KF6 because it will (most likely) break the current API.